The Battle of Irún became the decisive battle of the Campaign of Gipuzkoa prior to the War in the North during the Spanish Civil War. The Nationalist Army, under Alfonso Beorlegui, had to capture Irún to cut off the northern Basque provinces of Gipuzkoa, Biscay, plus Santander and Asturias from their source of arms and support in France.

After the coup of July 1936 Gipuzkoa had remained loyal to the Republic. But from the first outbreak of the uprising General Mola in Navarre had attempted to send columns to seize control of the province and cut off communication with the French border. The northern strip that remained loyal to the Republican government was geographically and politically isolated from the rest of the Republican territory, and was the only land route connecting the northern zone under Republican control with France. The eastern zone of Gipuzkoa was defended by a force of 2,000 men, comprised of loyalist soldiers, battalions of Asturian miners, and Basque anarchists, communists, and Basque nationalist (PNV) militias. They were poorly armed and had virtually no artillery. The Nationalist forces were no larger had heavy artillery and air reinforcements of Junkers Ju 52s. Mola’s forces were composed of professional military units and Carlist militias with pre-war military training.

On 27 July 1936, Beasain had become the first major town in Gipuzkoa to fall to the Nationalists. Its capture secured the southern entrance to the province and gave General Emilio Mola’s forces control of the main road and railway running north towards Tolosa, Donostia-San Sebastián, and Irún. The loss of the town also ended the Republican attempt to carry the war into neighbouring Álava and left the defenders on the strategic defensive for the remainder of the Gipuzkoa campaign. Following the failure of the military uprising in most of Gipuzkoa, Republican authorities hastily organised local militias, supported by members of the Guardia Civil, Miqueletes, and volunteers from nearby industrial towns such as Eibar. Their resources were limited. The bridge at La Caseta, near the Navarre frontier, was demolished in an attempt to delay the Nationalist advance, but Colonel Cayuela’s column crossed into Gipuzkoa through the Etxegarate Pass and steadily pushed north. At the same time, additional Nationalist forces under Commanders Albizu and Malcampo advanced along parallel routes through Zegama and Lazkao, concentrating against Beasain from three directions.

The Nationalists had also occupied Olaberria, immediately south of Beasain. Republican defenders withdrew into the town, where Captain Alejo Beñarán of the Guardia Civil attempted to organise a final defence with guardsmen from Eibar and local volunteers. Fighting centred on the railway station and the southern approaches, where the defenders resisted for several hours despite being heavily outnumbered. The capture of Olaberria Beasain had immediate strategic consequences. Nationalist forces now controlled the principal communications corridor through southern Gipuzkoa, allowing them to move men, artillery, and supplies north by road and rail. Republican plans to threaten Vitoria from Gipuzkoa were abandoned, and the front stabilised further north around Tolosa, Villabona, and eventually the approaches to Donostia-San Sebastián and Irún. The initiative had decisively passed to the Nationalists.

The occupation was also followed by severe repression. Captain Alejo Beñarán was captured and executed, while contemporary sources and later historical research indicate that around sixty people were shot in the aftermath. Nationalist soldiers, particularly Requeté volunteers, also looted abandoned homes with the acquiescence of some officers. The fall of Beasain therefore marked not only the beginning of the Nationalist conquest of Gipuzkoa but also the beginning of the repression that accompanied their advance through the province.

Nationalist pressure on the Basque coast extended on 8 August 1936, a Nationalist aircraft carried out the first aerial bombardment of Bilbao, dropping several bombs on the port of Santurtzi (Santurce). A week later, the Nationalist destroyer Velasco shelled the town again, striking the CAMPSA fuel depots and sending a large column of smoke into the air. Throughout August, Nationalist warships operating in the Bay of Biscay repeatedly bombarded Republican coastal batteries and towns along the Gipuzkoa coastline. The most destructive naval attack came when the battleship España shelled Donostia-San Sebastián, killing four people and wounding another thirty-eight. Republican authorities in the city had previously warned that they would execute prisoners if the bombardment continued.

The Nationalist offensive against Irún began on 9 August 1936, when Colonel Alfonso Beorlegui’s column advanced north from Navarre towards the Republican-held frontier. Rather than attacking the town directly, the Nationalists first had to force their way through a chain of steep wooded ridges that dominated every road leading to Irún. Republican engineers and militia had spent the previous weeks digging trenches, constructing barricades, and establishing machine-gun positions across the heights of Pikoketa, Erlaitz, Pagogaña, and San Marcial. From these positions they could observe the valleys below and direct fire onto any force attempting to approach the town.

The defenders came from a mixture of organisations. Assault Guards, Carabineros, Basque volunteers, local militia, Asturian miners, and members of socialist, communist, and anarchist organisations occupied the defensive line. Most had little formal military training, but they knew the terrain well and used the forests and rocky slopes to slow the advance. Their resistance forced Beorlegui’s troops to fight for every ridge rather than making a rapid march to the frontier.

Nationalist forces combined regular army units with Navarrese Requetés, Falangists, Guardia Civil, and other right-wing volunteers. Instead of relying on infantry attacks alone, they used concentrated artillery bombardments to break Republican positions before advancing. Aircraft also bombed defensive positions and roads behind the front, disrupting communications and making it increasingly difficult for the defenders to move men or supplies between sectors. On 9 August, the Beorlegui column launched a direct attack on Irún, which was fiercely repelled by the popular militias commanded by the communist Manuel Cristóbal Errandonea, as well as by the Carabineros commanded by Lieutenants Gómez and Ortega. The Nationalist changed tack and began bombarding the city with German Junkers bombers, and ships of the Cantabrian Fleet, which the rebels had managed to organize to blockade the ports of the Republican zone. On 11 August, the battleship España and the cruiser Almirante Cervera heavily bombarded the city. These attacks provoked the anger of the militiamen, who, in retaliation, executed numerous military personnel and right-wingers who had been imprisoned in the Guadalupe fortress since the uprising of 18 July.

• Pikoketa

On the morning of 11 August 1936, Nationalist forces launched the opening attack of their offensive against Irún by striking the Republican outpost at Pikoketa, a hill overlooking the Oiartzun valley and guarding the approaches to the main defensive line at Erlaitz and Pagogaña. Although small, the position formed the northern anchor of the Republic’s forward screen. If it fell, Nationalist troops would gain a direct route towards the stronger mountain defences protecting Irún.

The position was held by only around sixteen defenders, consisting mainly of young volunteers from the Communist Youth of Irún together with several Carabineros. They possessed a single Hotchkiss machine gun, rifles and limited ammunition. Before dawn, troops from Colonel Beorlegui’s Los Arcos Column, supported by artillery that had recently arrived from Navarre, advanced from the Oiartzun area and surrounded the hill. When the attackers reached the Republican trenches they came under machine-gun and rifle fire, forcing them to deploy before storming the position.

The defenders resisted briefly but were heavily outnumbered. According to the Nationalist operational diary, nine defenders were killed during the assault, while seven were captured. Rather than being treated as prisoners of war, the captives were taken to nearby Pikoketa farmhouse and executed shortly afterwards. The attackers then turned the captured Hotchkiss machine gun against Republican troops retreating towards Erlaitz, killing several more as they withdrew. Although Nationalist reports claimed fourteen enemy dead in total, later investigations suggest that many of those listed as combat casualties were in fact prisoners executed after the battle.

Among those killed were some of the youngest volunteers on the Irún front. They included Mercedes López Cotarelo, aged 16, and Pilar Vallés Vicuña, aged 18, both members of the Communist Youth, together with Carabineros and local militia from Irún. The two female militia members were raped and tortured, their breasts cut off and their bodies were then buried in a mass grave. Alongside the girls, are José María Arruti Idiaquez, 18, Victor Genua Montiano. 25, Jesús López Casado, 26, Agapito Domínguez Taguada, 23, Bernardo Usabiaga Jauregui,  17, Manuel Justo Alberti, 22, Miguel Jacinto López, 39, Vicente Argote, 40, Agustín Miguel Bermejo, 39, Félix Luz Echevería,  27, and Ángel Braña López, 27.

The loss of Pikoketa did not immediately break the Republican front, but it gave the Nationalists control of the first defensive line and allowed them to move their artillery and supplies closer to Erlaitz. Over the following days they consolidated the captured ground before beginning their assault on the stronger mountain positions. The fighting for Irún had entered a new phase in which the Republic could no longer rely on delaying actions alone; it would have to defend the heights overlooking the city itself.

The military situation steadily worsened for the Republic. Ammunition became increasingly scarce as French authorities imposed tighter controls on arms crossing the frontier, while casualties reduced the strength of units that could not easily be replaced. Although Republican forces continued to counterattack whenever opportunities arose, they could no longer prevent the Nationalists from bringing more artillery within range of Irún itself.

• Tolosa, Villabona, and Andoain

The capture of Beasain had opened the principal route through the Oria valley and forced Republican forces to establish a new defensive line around Tolosa, Villabona, and Andoain. These towns lay astride the main road and railway linking Vitoria with Donostia-San Sebastián and Irún, making them the next objectives for General Emilio Mola’s offensive into Gipuzkoa. Republican militia, Assault Guards, Guardia Civil loyal to the Republic, and Basque volunteers attempted to delay the advance by occupying the surrounding hills, destroying bridges, and blocking the highway, but they lacked sufficient artillery and ammunition to hold the line indefinitely.  Nationalist columns had advanced steadily north during the final days of July, supported by artillery brought through the Etxegarate Pass. Rather than launching a single assault, they pressed forward in stages, forcing the Republicans to abandon one defensive position after another. Villages overlooking the valley changed hands as the defenders withdrew towards the larger towns. The Republican command recognised that preserving its limited forces was more important than defending every settlement, and increasingly chose delaying actions before retreating north. Villabona fell first and Republican forces withdrew after brief fighting, destroying bridges and attempting to slow the Nationalist pursuit. The loss of the town exposed the southern approaches to Tolosa and enabled Nationalist artillery to move closer to the Republican positions defending the provincial capital of the valley.

Tolosa was also occupied on 11 August after Republican forces abandoned the town rather than risk encirclement. Although fighting occurred on the surrounding heights and along the approaches, the withdrawal meant that Tolosa escaped the extensive destruction later suffered by Irún. Its capture gave the Nationalists control of one of Gipuzkoa’s most important administrative and communications centres, including the railway, road junctions, and crossings over the Oria River. The fall of Tolosa also provided a secure logistical base from which supplies, artillery, and reinforcements could be pushed further north.

On the same day, Nationalist troops entered Andoain, only 16km from Donostia-San Sebastián. Republican units again withdrew after delaying the advance, avoiding a costly stand inside the town. The occupation of Andoain brought the Nationalists to the southern outskirts of Donostia-San Sebastián and completed their control of the lower Oria valley. With Tolosa and Andoain in Nationalist hands, Republican forces had lost the last significant defensive positions south of the provincial capital.

The capture of these three towns fundamentally altered the campaign in Gipuzkoa. The Nationalists now controlled the province’s principal north-south transport corridor and could concentrate their efforts on the two remaining Republican strongholds: Donostia-San Sebastián and Irún. The Republican army had succeeded in delaying Mola’s advance for several weeks, but each withdrawal reduced the territory under its control and brought the Nationalists closer to the French frontier. After the loss of Tolosa, Villabona, and Andoain, the decisive battles for Gipuzkoa would be fought around Donostia-San Sebastián and on the mountain defences protecting Irún.

• Irún

By 20 August, Nationalist artillery dominated the hills overlooking Irún and subjected the town to sustained bombardment. Shells struck defensive positions, roads, and buildings throughout the day as infantry prepared for the final assault. Republican commanders attempted to organise a defence within the town itself, erecting barricades across major streets and establishing machine-gun positions to cover bridges, crossroads, and key public buildings. Houses became improvised strongpoints as civilians sheltered from the bombardment or prepared to flee towards the French frontier.

On 21 August, after nearly two weeks of fighting through the mountains south of the town, Nationalist infantry broke through the remaining Republican positions and advanced into Irún from the direction of San Marcial and the southern suburbs. The assault followed days of relentless artillery bombardment, naval shelling from the battleship España and the cruiser Almirante Cervera, and repeated air attacks that had steadily weakened the defenders. Although the Republican line on the surrounding heights had collapsed, resistance inside the town remained determined. Militiamen, Assault Guards, Carabineros, and loyal soldiers fought from barricades, houses, and public buildings, forcing the attackers to clear the streets one block at a time.

The fighting quickly developed into a series of local engagements as Republican units withdrew northwards through the town. Barricades built from paving stones, overturned vehicles, furniture, and timber blocked the principal roads, while machine-gun teams covered bridges, crossroads, and railway crossings. Riflemen occupied upper floors and rooftops before falling back to the next prepared position. The objective was no longer to hold Irún permanently but to delay the Nationalist advance long enough for military units, equipment, and as many civilians as possible to escape across the international bridge into France.

Republican engineers systematically destroyed bridges, railway installations, telephone exchanges, and other infrastructure as they retreated. Railway rolling stock was disabled or abandoned, roads were obstructed with rubble, and demolitions were carried out wherever they might delay the advancing Nationalists. These measures slowed the pursuit only briefly, as the attackers steadily cleared each obstacle and continued towards the Bidasoa River.

As organised resistance collapsed, large fires spread through the centre of Irún. Flames engulfed entire streets, destroying homes, businesses, warehouses, and public buildings, while dense columns of black smoke rose high above the town and were clearly visible from Hendaye, where crowds gathered on the French riverbank to watch the destruction unfold. Foreign correspondents and photographers, including several working for the international press, recorded the burning town from across the frontier, producing some of the most recognisable images of the early Civil War. Their photographs were reproduced in newspapers throughout Europe and North America, making the destruction of Irún one of the first widely reported episodes of the conflict.

Responsibility for the fires became the subject of immediate propaganda. Nationalist authorities claimed that retreating Republican forces had deliberately burned the town as an act of vengeance before fleeing into France. Republican leaders rejected this accusation, arguing that the fires had largely been started by days of artillery bombardment, aerial bombing, naval shelling, and the close-quarters fighting taking place throughout the streets. Modern research suggests that neither explanation alone accounts for the scale of the destruction. Republican engineers almost certainly set fire to or demolished some buildings and infrastructure with military value during their withdrawal, while artillery impacts ignited additional fires that spread rapidly through closely packed buildings, fuel stores, and timber roofs. Once the flames gained hold, the continuing battle made organised firefighting virtually impossible. Most historians therefore conclude that Irún was destroyed by a combination of deliberate military demolitions, bombardment, and uncontrolled urban fires rather than by a single planned act.

Behind the front line, the roads leading to the frontier filled with civilians fleeing the fighting. Thousands crossed the Bidasoa River carrying children, elderly relatives, bedding, clothing, and whatever possessions they could transport by hand or cart. Republican soldiers, wounded men, and refugees became intermingled in long columns moving towards the international bridge, creating scenes of confusion as shells continued to fall nearby. Many believed they would be able to return within days once the battle ended. Instead, for a large number of Basque families, the crossing into France marked the beginning of a prolonged exile that would last months or years.

By the evening of 21 August, organised Republican resistance inside Irún had ended. Nationalist troops secured the town, occupied the international bridge, and closed the Republic’s most important land crossing with France in the northern zone. The loss of Irún deprived Republican Gipuzkoa of its principal route for receiving arms, ammunition, volunteers, and refugees. It also left Donostia-San Sebastián strategically isolated, with the city’s defenders now facing the Nationalist advance without a direct overland connection to France. The fall of Irún therefore marked the decisive turning point in the Gipuzkoa campaign and paved the way for the capture of Donostia-San Sebastián less than a month later.

• The Bidasoa front, San Marcial, Behobia, Hernani, Buruntza, Santa Bárbara, Oriamendi, Santiago Mendi, Astigarraga, Errenteria

Between 21 and 30 August 1936, the campaign in Gipuzkoa entered a transitional phase. The decisive fighting remained centred on Irún, while the remainder of the front was relatively static. Rather than launching a simultaneous advance on Donostia-San Sebastián, General Mola concentrated his available troops, artillery, and ammunition on capturing the French frontier before turning west against the provincial capital.

Along the Bidasoa front, the Nationalists consolidated the gains made on 21 August after entering Irún’s outskirts. They brought additional artillery forward onto the captured heights, reorganised Beorlegui’s column, and prepared for the final assault against the remaining Republican positions around San Marcial, Behobia, and the Puntxa Carabineros barracks. The Republicans, meanwhile, received only limited reinforcements and continued to suffer from a severe shortage of rifle ammunition, despite the French frontier remaining technically open. Their commanders used the remaining days of August to strengthen the final defensive line protecting the international bridge.

Further west, on the Oria front, there was comparatively little movement. The Nationalists had already reached the approaches to Andoain and Hernani, but they deliberately avoided a costly frontal attack while Irún remained unconquered. Instead, both sides fortified their positions. Republican forces constructed a continuous defensive line across the hills of Buruntza, Santa Bárbara, Oriamendi, and Santiago Mendi, linking with the defences around Astigarraga and Errenteria. Nationalist artillery periodically shelled these positions, but neither side attempted a major offensive during the last ten days of August.

In Donostia-San Sebastián, the Republican authorities recognised that the loss of Irún would leave the city strategically exposed. The War Commissariat ordered additional mobilisation of carpenters, labourers, electricians, builders, and other skilled workers to construct fortifications and support the front, while trained military marksmen were recalled for active service. Preparations accelerated as it became increasingly clear that the defence of the provincial capital would depend upon the outcome of the battle at Irún.

The Nationalists also continued to tighten the pressure through bombardment. Artillery batteries fired on Republican positions almost daily, while aircraft attacked roads and communications behind the front. The intention was not only to inflict casualties but also to prevent the movement of reinforcements and supplies between Donostia-San Sebastián and Irún. This sustained pressure gradually weakened the Republican defence, even before the final assault began.

By 30 August, the strategic situation had become increasingly unfavourable for the Republic. Irún remained under Republican control, but the defenders had been compressed into a narrow perimeter around the town and the French frontier. Nationalist forces held the surrounding high ground, controlled the initiative, and were preparing the attacks that would capture San Marcial in early September. Once Irún fell, the road to San Sebastián would lie open, and the entire Republican position in Gipuzkoa would become untenable.

• Gijón, Asturias

When August began, the military rebellion in Gijón had been reduced to two isolated positions in the southern part of the city – the Simancas infantry barracks and the nearby El Coto barracks occupied by engineers. The original rebel force in Gijón had numbered roughly 500–600 men. Around 350 belonged to Colonel Antonio Pinilla’s Simancas Mountain Infantry Regiment, while approximately 180 engineers were based at El Coto and a smaller number of Falangists and other civilian supporters joined them.

Outside these positions, Gijón was controlled by the Republic. The city had approximately 100,000 inhabitants, and several thousand armed workers and militiamen were available to the Republican authorities. The attackers had a large numerical advantage and access to machine guns, artillery, dynamite, armoured vehicles, and a small number of aircraft and the two barracks had already been under siege for almost two weeks. Republican forces occupied surrounding streets and buildings, establishing firing positions close to the compounds. Artillery was brought into the city to fire directly against them. Miners within the militia used dynamite against walls and defended positions, while rifle and machine-gun fire made movement outside the buildings dangerous.

The Nationalists had no outside support on land, but the navy could reach Gijón from the sea. The cruiser Almirante Cervera operated off the Asturian coast and repeatedly bombarded Republican positions around the city. The battleship España and destroyer Velasco also appeared in operations off the coast. Their naval guns considerably outranged the weapons available to most Republican militia, and the bombardments killed civilians as well as combatants. Across the fighting around Simancas and El Coto, more than 50 civilians were killed by naval and aerial attacks. The overall death toll associated with the battle exceeded 100. The presence of several hundred isolated rebels exposed a city of approximately 100,000 people to repeated naval and aerial attack for more than a month.

Inside the barracks, the principal problem was supply. Pinilla’s Nationalists could not replace ammunition, food, medicine, or personnel lost during the fighting. Water became increasingly difficult to obtain as the siege continued. Wounded men had to be treated inside the compound with whatever medical supplies remained. The naval vessels offshore could fire into Gijón but could not deliver enough supplies or reinforcements to change this situation while Republicans were using artillery, dynamite, and miners began excavating toward the Nationalist positions. On 12 August work began on a tunnel intended to allow explosives to be placed beneath or close to the barracks. The attempt led to fighting around the excavation.

El Coto barracks was becoming harder to maintain separately from Simancas. Republican pressure against the engineer barracks increased during the middle of August. Its loss would leave Pinilla’s men concentrated in a single compound and allow the attackers to focus their weapons on Simancas, but on 16 August, the Republicans finally broke through, and surviving Nationalists had to get to Simancas to hide in the remaining battleground.

Republican attacks continued over the following days. Artillery progressively broke walls and buildings while rifle and machine-gun fire covered attempts to approach the perimeter. Dynamite was used at close range despite the Nationalist aircraft above, and ships continued attempting to suppress Republican positions from offshore. By 20 August, the Nationalist rebels had been isolated for more than a month. The original force had been reduced by casualties, and many of the survivors were wounded. Later Nationalist accounts place slightly more than 200 men inside Simancas during the final stage of the siege. The exact Republican strength committed to the last attacks is uncertain. Nationalist accounts claimed more than 10,000 militiamen around the barracks, but this figure may represent the total armed forces available in Gijón.

The final attack began on 21 August. Republican artillery and aircraft struck the remaining buildings before militia advanced against the perimeter and armoured vehicle was used against one of the entrances. Once openings were made in the defences, Republican fighters entered the compound and fighting moved into the courtyards and ruined buildings. Nationalist Colonel Pinilla was killed during the final fighting while other officers and soldiers died as resistance broke into separate groups within the complex. By early afternoon, organised resistance had ended. After 33 days, the Nationalist enclave inside Gijón finally ceased to exist.

Prisoners and wounded men were taken from the ruins, but some were killed after capture. Accounts include wounded prisoners being removed toward the beach and shot. The violence surrounding the collapse of the barracks makes an exact division between men killed while fighting and those executed immediately afterward difficult to establish. The Republicans entered a complex that had been heavily damaged by weeks of artillery, dynamite, aerial attack, and close-range fighting. Photographs taken by Constantino Suárez on 21 August record militia around the shattered buildings and provide some of the clearest surviving visual evidence of the final hours of the siege. More 100 rebels and civilians had been killed around Simancas and El Coto, and another 50 civilians had died in naval and aerial attacks.