Il’ya Finn took part in the Spanish Civil War where he served in the 1^a Escuadrilla of Grupo 26.

He arrived in Spain on 5 September 1937

In October, his unit was based at Sagunto and Sabadal airfields, operating over Barcelona and Valencia.

On 12 October 1937, Finn (1^a/26) claimed a shared Ju 52/3m or Ju 86 over Huesca together with Kapitan Anatoly Serov (1^a/26) and Starshii Leitenant Yevgeniy Stepanov.
Nationalist records do not confirm this loss.

At 03:00 on the night of 24-25 October three S.81s of the 251^a Squadriglia, XXV Gruppo B.N. took off from Alcudia to bomb the airport of Sabadell. The plan was that the formation leader Capitano Nicola Ruggeri should drop his war-load first, so that the fires caused by his incendiary bombs should allow the other two crews, with aircraft carrying 15kg high explosive bombs, to choose the best targets. Reaching their target at a level of 700 meters, the tri-motors were met by the fire of machine-guns placed on the hills south-west of the airfield, and then they were attacked by an I-15 flown by Starshii Leitenant Yevgeniy Stepanov (1^a/26). Stepanov had taken of together with another I-15 flown by Finn. Stepanov shot down the second aircraft, flown by Tenente Ezio Maccani, which crashed in flames near Montcada, setting fire to a large wooded area and killing the whole crew of five. He then tried to ram the third S.81 with the left leg of his I-15s undercarriage. The S.81, which was badly hit, manage however to keep contact with his leader. The two diverted to the secondary target, the explosive factory of Badalona, which they bombed at 04:35.
Stepanov returned claiming two victories. According to some sources Finn is credited with the second S.81.
Maccani was posthumously decorated with the Medaglia d’oro al valor militare.
Stepanov was decorated with the Order of the Red Banner for this combat and promoted to Kapitan.

Shortly after this (according to some sources already on 26 October), Finn left Spain.

Finn claimed one shared biplane victory during the Spanish Civil War.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1937
	12/10/37		1/3	Ju 52 (a)	Shared destroyed	I-15		Huesca area	1a/Gr. 26

Biplane victories: 1 shared destroyed.
TOTAL: 1 shared destroyed.
(a) May alternatively have been a Junkers Ju 86. Not confirmed with Nationalist records.

Sources:
Air Aces Home Page - Jan Safarik
Caballeros del aire de la Guerra Civil Española (1936-1939)
Carlos Castejon - Soviet Volunteer in the Spanish Civil War - Igor Gordelianov and Mikhail Zhirokhov with editorial assistance by Richard Karbowski, 2002 Small Air Forces Observer no. 100 kindly provided by Mikhail Zhirokhov
Geroi Sowetskogo Soyuza, 1987-1988 Moscow kindly provided by Sergey Abrosov
Stalin's Falcons - Tomas Polak and Christhoper Shores, 1999 Grub Street, London, ISBN 1-902304-01-2
The Legion Condor - Karl Ries and Hans Ring, 1992 Schiffer Publishing, ISBN 0-88740-339-5