'Rügen' (i) was the German and Italian bombing of the Basque town of Guernica during the Spanish Civil War (26 April 1937).

The attack was undertaken by German and Italian aircraft of the Luftwaffe’s Legion Condor and the Regia Aeronautica’s Aviazione Legionaria, and caused the deaths of 1,654 persons on the ground according to the Basque government of the time, although modern research suggests between 200 to 400 persons were killed. The Western countries viewed Guernica as the first example of the currently held concept of 'terror bombing'.

Guernica (Gernika in Basque) was a centre of great significance to the Basque people before and after the air raid which made it notorious. Traditionally, the important administrative body, the Biscayne assembly, had met in the town under an oak tree, the Gernikako Arbola. At this time the advances of General Francisco Franco y Bahamode’s Nationalist rebel troops had eaten into the territory controlled by the Republican government. The Basque government, an autonomous regional administrative body formed by Basque nationalists and leftists, sought to defend Biscay and parts of Guipuzcoa with its own small and lightly equipped Basque army.

At the time of the raid, Guernica represented a focal strategic point for the Republican forces as it stood between the Nationalists and the capture of Bilbao, which was seen as key to bringing the Spanish Civil War to an end in the north of Spain. Guernica was also the path of retreat for the Republicans from the north-eastern part of Biscay.

Before the German and Italian air attack, the town had not been directly involved in the fighting, although there were Republican forces in the area, including 23 battalions of Basque army along the front to the east of Guernica. The town also housed two Basque army battalions, but had no static air defences, and it is thought that no Republican air cover could be provided as a result of the Republican air force’s recent losses.

Guernica had a population of about 5,000, and is also believed to have accommodated numerous refugees fleeing into Republican-controlled territory. The raid also took place on a Monday, when there was generally a market which attracted people from the surrounding areas. There is still debate about whether or not a market was being held on that particular Monday: the Basque government had ordered a general halt to markets to prevent blockage of roads, and had also placed a restriction on the gathering of large numbers of people. There is doubt, however, that the directive had been received or was being obeyed by all areas, including Guernica, at the time of the raid.

The Legion Condor was under the command of the Nationalist forces, and the order to undertake the raid was transmitted to the Legion Condor's commander, Generalleutnant Hugo Sperrle, and his chief-of-staff, Oberstleutnant Wolfram Freiherr von Richthofen. While questions are often raised over the intent of the raid, the diaries of the planner and commander of the mission later indicated that an attack on Guernica represented part of a wider Nationalist advance in the area and was also designed to support Franco’s forces already operating in the area. von Richthofen, understanding the strategic importance of the town in the advance on Bilbao and restricting Republican retreat, ordered an attack against the roads and bridge in the Renteria suburb: the destruction of the bridge was considered the primary objective since the raid was to operate in conjunction with Nationalist troop movements against Republicans around Marquina. Secondary objectives were the restriction of Republican traffic and/or equipment movements and the prevention of bridge repair via the creation of rubble around the bridge.

To meet these objectives, the Germans committed two Heinkel He 111, one Dornier Do 17 and 18 Junkers Ju 52 'Behelfsbomber' aircraft, and the Italians three Savoia-Marchetti SM.79 aircraft. The aircraft carried 250- and 25-lb (551- and 55-lb) HE bombs as well as 2.2-lb (1-kg) incendiaries.

he first wave of bombers arrived over Guernica at about 16.30 and the attack started as a single Do 17, arriving from the south, dropped about 12 110-lb (50-kg) bombs. The three SM.79 bombers had taken off from Soria at 15.30 with orders, as the second wave, to 'bomb the road and bridge to the east of Guernica, in order to block the enemy retreat'. The orders stated explicitly that the aircraft were not to bomb the town itself. During a single 60-second pass over the town, from north to south, the SM.79 bombers dropped 36 110-lb (50-kg) bombs. The third, fourth and fifth waves now followed, and ended at about 18.00. The third wave consisted of one He 111 escorted by five Aviazione Legionaria Fiat fighters. The fourth and fifth waves comprised German bombers.

Earlier, at about 12.00, Ju 52 bomber/transports of the Legion Condoe had carried out a mission around Guerriciaz (Gerrikaraiz). After this they landed to rearm and then took off to complete the raid on Guernica. The attack was to fly over the target area from north to south, coming from the Bay of Biscay and up the course of the estuary of the Urdaibai river. The 1./K88 and 2./K88 squadrons of the Legion Condor took off at about 16.30, and the 3./K88 squadron lifted off from Burgos a few minutes later. They were escorted from Vitoria by a squadron of Fiat fighters and also Messerschmitt Bf 109B fighters of Oberleutnant Günther Lützow’s 2./J88 squadron. This force totalled 29 aircraft, and between 18.30 to 18.45 each of the three bomber squadrons attacked in a formation of three Ju 52/3m machines abreast, representing an attack front of about 165 yards (150 m).

At the same time, and continuing for some 15 minutes after the bombing, Bf 109B monoplane and Heinkel He 51 biplane fighters strafed the roads leading out of town, adding to the civilian casualties.

The bombing shattered the determination of Guernica’s defenders, allowing the Nationalists to overrun the town, which had been largely destroyed. Three quarters of the town’s buildings were reported completely destroyed, and most others had sustained damage. von Richthofen recorded that the bridge was not destroyed or even hit during the raid, and the mission was therefore considered a failure, although the rubble and chaos that the raid created severely restricted the movement of the Republican forces.