Jim Allison was an ex- U.S. Navy pilot, who arrived in Spain on 9 December 1936 where he was sent to Valencia for certification.

In the beginning of February 1937, Andrés García La Calle was put in command of the first Spanish Chato (Polikarpov I-15) Squadron.
Initially it consisted of the following pilots: La Calle, Castañeda, Ben Leider, José Calderón, Allison, Frank Tinker, Harold Dahl, Pepito ’Chang’ Sellés, Bercial, Ortiz, Gil and Riverola.

On 7 February, the squadron moved to the old Hispano Suiza aerodrome in Guadalajara. They began operations at El Jarama, where their activities were outstanding, but their losses heavy.

In the early morning on 18 February, two Nationalist Ro.37s (flown by Spanish pilots) took off, followed by three Ju 52/3ms escorted by the Spanish Patrulla Azul and the Italian Fiat Group, which now had 24 aircraft. When they arrived over the front at el Jarama, the CR.32s turned so that they were patrolling parallel to the front, while the I-15s waited on the other side. The Ro.37s and Ju 52/3ms crossed into enemy territory and were attacked immediately. Joaquín García-Morato at once broke formation and, followed by Julio Salvador Díaz-Benjumea and Bermúdez de Castro, launched himself into the battle. The Italians hesitated until Capitano Nobili, who was leading a Squadriglia, also broke from formation and went to help his companions. Finally, the entire group took part in the battle, and was so successful that they destroyed eight Republican fighters for the loss of only one of their number (three according to some sources). One I-16 and two shared I-15s were claimed by Tenente Enrico Degli Incerti while Sergente Maggiore Silvio Costigliolo claimed an I-15 in the Arganda area. The Spaniards Morato and Salvador also claimed a victory each.
This battle was fought against the ”Chatos” of the Escuadrilla de La Calle. The Republican pilots reported being engaged by 85 Heinkel He 51s over the front. Immediately the Escuadrilla went into a tight horizontal circle (”Lufbery circle”). The first enemy aircraft fired randomly at the I-15s as they dived past the Escuadrilla’s defensive pattern. Unwillingly to challenge the Republican fighters, the remainder of the Nationalist pilots followed suit, executing a single strafing pass, and then flying lazily below the I-15s in hopes of enticing a few green Republican pilots away of the defensive protection. Ben Leider took the bait and started down after one of the easy-looking targets, only to attract three enemy fighters on his tail. As Frank Tinker peered over his shoulder during the swirling melee of aircraft, he saw Leider’s I-15 to shudder as the CR.32s flashed past. Tinker’s heart sank as he noticed Leider veer toward friendly territory in a shallow dive. Twice, Leider tried to land his fighter in a small field before slamming into the side of a hill, killing him.
The Escuadrilla leader Andrés García La Calle’s version of Leider’s end differed markedly from Tinker’s perspective. As Leider dived, breaking away from the ”Lufbery circle” to attack a “Heinkel” below, an enemy fighter locked on his tail. La Calle pulled behind Leider’s pursuer and frightened him away with his machineguns. Repeatedly La Calle then tried to herd Leider’s intended victim back away from Nationalist lines so that the American could down the enemy fighter. La Calle wanted Leider to destroy the enemy fighter as a morale boost for the Escuadrilla and to appease Leider’s Communist backers. When the Nationalist pilot made a third attempt to cross his lines, La Calle shot him down. Irritated by the turn of events and Leider’s seeming inability to shoot down his adversary, the Spanish Commander signalled Leider to head for home. During the flight back to base, Leider flew just behind the Escuadrille leader’s wing. Halfway home, La Calle glanced around only to discover that Leider was gone. Having landed he learned that no one knew of the American’s whereabouts: his comrades saw him rejoin their homebound group and never again. There was no other news until Leider’s ”Chato” was located.
Evidence from the crash site gave Leider’s fellow pilots a clue as to his final seconds on earth. During the dogfight, three rounds penetrated his cockpit, one passing through his leg. Instinctively he loosened his seat belt and harness. As Leider prepared to bale out, he had second thoughts about giving up his I-15, so he decided to attempt to set down his aircraft. His loss of blood caused him to faint at the controls.
Allison and Harold Dahl followed Leider down after the Nationalist fighters. Allison shot down his intended victim before three enemy fighters reached him. Allison’s I-15 gave a jerk, then it executed a perfect Immelmann and headed back to base but he was forced to make an emergency landing. Allison had received a serious leg wound during the combat. Dahl prepared to trip his guns on a careless adversary when he noticed the same three enemy fighters flash past. Almost simultaneously, he became aware that his machine was not answering the controls. A glance back revealed that the entire tail of his fighter had been shot away.
The remaining I-15s of the Escuadrilla de La Calle maintained the ”Lufbery circle” when another Escuadrilla of I-15s appeared piloted by Russian volunteers. Fighting their way through the curtain of enemy fighters, the Soviets joined La Calle’s men in the wheel formation until the two Escuadrillas were rescued by a third Escuadrilla of I-16s. Totally, the Republican pilots claimed seven enemy fighters for the loss of five aircraft. Both Allison and Dahl rejoined their unit the next day.

Allison’s leg wound was serious and he went to the American Hospital in Neuilly, where the doctors saved his leg.

He left for home in March 1937.

Allison ended the war with one biplane victory.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1937
1	18/02/37	morning	1	CR.32 (a)	Destroyed	I-15		Jarama area	Escuadrilla de La Calle

Biplane victories: 1 destroyed.
TOTAL: 1 destroyed.
(a) During the combat the Nationalist pilots claimed eight enemy aircraft for the loss of one CR32 while the Republican pilots claimed seven enemy aircraft for the loss of five aircraft.

Sources:
Airmen without a portfolio: U.S. mercenaries in civil war Spain - John Carver Edwards, 2003 Global Book Publisher, ISBN 1-59457-175-9
Air War over Spain - Jesus Salas Larrazabal, 1974 Ian Allan Ltd, Shepperton, Surrey, ISBN 0-7110-0521-4
Flyers of Fortune
Några leva än - F. G. Tinker, 1939 T. V. Scheutz Bokförlag AB, Stockholm
Polikarpov Fighters in action Pt. 1 - Hans-Heiri Stapfer, 1995 Squadron/Signal Publications, Carrollton, ISBN 0-89747-343-4
Additional information kindly provided by Simon Buckley, Eugenio Costigliolo and Mikhail Zhirokhov.