Tupolev SB in Spain. Part one.

 

In the early days of the Spanish Civil War, the Soviet freighter ship Komsomol shipped the first 31 Tupolev SB bombers from Odessa to the port of Cartagena, Murcia, south-eastern Spain. The Spanish Republican Government did pay  $110.000 US dollars per aircraft. Those SBs were part of one of the first production batches completed at GAZ-22 factory. They were unloaded on 15th October 1936 and assembles at Los Alcázares airfield, in the region of Murcia. 
The bombers were assigned to Grupo 12 (Group 12), which also operated the Polikarpov I-15 and I-16 fighters. Flying personnel, most of them, were Soviet, however, some Spanish and other international volunteers worked with the Grupo from its origin. Since the beginning of the conflict the SB was nicknamed as Katiuska by the Spaniards, after a popular character of a Spanish operetta, back at the time.

On 28th October 1936 the SBs flew their first combat mission when four Katiuskas belonging to 1ª Escuadrilla / Grupo 12 (1st Squadron / Group 12), under the command of the Swiss Ernst Schacht raided the Tablada airfield at Seville. After the attack, the SBs flew away at very high speeds, so Nationalists fighters couldn't intercept them, causing consternation among the Nationalists.

On 1st November 1936, three Katiuskas attacked the Gamonal airfield, in the city of Burgos, destroying six Fiat Cr.32 Italian fighters on the ground. The next day, two Cr.32 shot down one SB 2M-100 over Talavera, in new Castile. This loss showed its main flaw: the lack of both crew armour and self-sealing fuel tanks. 

On 6th November 1936 the SBs raided the airfield of Ávila, old Castile, destroying two Heinkel He.51 fighters of the German Condor Legion. These kind of raids, where a small group of Katiuskas targeted Nationalists airfields were very common in the months of November and December 1936. The first Spanish Nationalist pilot to claim a downed SB 2M-100 was Bermúdez de Castro. On 7th December he shot down a Soviet bomber over Castilblanco, Extremadura. By the end of the year 1936, Grupo 12 had lost a total of six out of 31 Katiuskas to various reasons.

In January 1937 the 1ª and 2ª Escuadrillas (1st and 2nd Squadrons) of Grupo 12, flew missions from Marbella, Andalusia, to try to stop the Nationalist advance on Málaga. On 20th January, some Nationalists strongpoints in Ceuta (Spanish Morocco) were bombed. During early March, the Katiuskas took part in the Battle of Guadalajara (old Castile) by bombing positions of the Italian Expeditionary Force. On 29th May 1937 two Katiuskas attacked the German Deutschland Panzerschiffe (Armoured Cruiser), off the coast of Ibiza, damaging moderately the cruiser in the attack.

The cargo freight SS Aldecoa arrived at the port of Cartagena on 24th June 1937 with 21 more Katiuskas, these were complemented with 10 additional ones shipped by the freighter SS Artea Mendi the next 1st July. This second batch was composed of the more powerful and improved SB 2M-100A model. The 31 new Katiuskas were assembled at San Javier, Murcia and Líria, in Valencia. They were assigned both to Grupo 12 and the newly formed Grupo 24. This new group flew its first combat mission on 3rd July when its two squadrons raided Talavera, Salamanca and Ávila. 

Both Grupos saw action during the Republican Offensive in Brunete (west of Madrid) on 6th July 1937. On 8th July a Katiuska was shot down by a Messerschmitt Bf.109B of the Condor Legion. Four days later, a Katiuska managed to shot down a Bf.109B that was attacking the formation of bombers.

In the Fall of 1937 Soviet crews were withdrawn and replaced by Spanish personnel, leading to the dissolution of Grupo 12 and assigning every Katiuska to Grupo 24. 

Sources:

1st Signal Squadron - Aircraft In action 194 - Tupolev SB in Action

2nd https://en.wikipedia.org/wiki/Tupolev_SB

3rd https://massimotessitori.altervista.org/sovietwarplanes/pages/sb/tapani/spanish/spanishrepublican.htm