On 17 April 1937, the three Nationalist He 51 escuadrillas operated over the Teruel front with a total of 17 fighters.
2-E-2, with five He 51s, saw an enemy bomber but was unable to close with it. Shortly after they were joined by another He 51, flown by teniente Jaime Palmero Palmeta, and caught sight of ten I-15s patrolling well above their own altitude of 4,000m. They climbed to attack, determined to break off at the moment of interception, but teniente Palmero was unable to evade one I-15 that was coming down very fast in a dive, and the two machines collided. The ensuing combat ranged all over the sky, and ten more I-15s and a third fighter squadron soon joined the battle against the five remaining aircraft of 2-E-2. Capitán Ángel Salas Larrazábal made attacks on four aircraft but didn’t claim anything and arrived at Calamocha with his petrol tanks almost dry and with 18 bullet holes in the fuselage and wings. He had remained in the combat area until all the Republican fighters had disappeared. Alferéz Jorge Muntadas Claramunt, alferéz Rafael Mazarredo Trenor and alferéz Joaquín Ansaldo Vejarano had already landed at Calamocha, and only Ansaldo’s aircraft was free from damage. The fifth pilot, alférez Javier Allende Isasi was shot down by alferéz Juan Comas Borrás of 2^a/16. Allende’s fighter was seriously damaged and chivalrously escorted by Comas it until Allende was able to make a forced-landing in Nationalist-held territory.
2-E-2 had alone been involved in this combat, the other two He 51 escuadrillas were unaware of the action and were patrolling peacefully over their own lines.
Nationalist observers on the ground saw seven aircraft fall, and if one discounts the two He 51s flown by Palmero and Allende, this gives the destruction of five I-15s, but the Nationalist communiqué claimed a total of seven aircraft destroyed.
It seems that 18-21 I-15s were involved since it’s known that three escuadrillas took part in the combat; 1^a/16 (Escuadrilla La Calle), 2^a/16 and Escuadrilla Kazakov (the two last escuadrillas operated from the same airfield near Sarrion) and five claims are known. The 2^a/16 was first to engage, followed by Escuadrilla Kazakov and finally by the 1^a/16.
Additional to Comas’ claim of Allende, Albert Baumler (Escuadrilla Kazakov) reported that on his second mission of the day, his group intercepted a formation of Heinkel He 51 pursuits. Giving chase to the enemy, Baumler crippled a Heinkel; as he did not see it crash, he was awarded with only a probable victory. He did, however, obtain credit for a subsequent "kill" in this same combat. Aleksandr Osadchiy, CO of Escuadrilla Kazakov claimed two He 51 while Frank Tinker from the 1^a/16 claimed a He 51while flying in I-15 CA-058.
The I-15 that collided with teniente Palmero was flown by Alfonso Calvo Ortíz of the 2^a/16, who also was killed.
It seems that Manuel Aguirre Lopez of Escuadrilla Kazakov also took part in this combat but without claiming anything.

The all-Spanish Fiat Grupo, with the designation 2-G-3, was formed in Cordoba on 4 May 1937 from the escuadrillas led by capitán Joaquín García Morato and capitán Ángel Salas (2-E-3). Morato assumed command of the Grupo, and Julio Salvador took over leadership of Morato’s old escuadrilla (1-E-3).
This had been made possible after a further consignment of eight CR.32s had been passed on to the Nationalist air force in April 1937, and they joined the five previously handed over four months earlier to form the basis of the first Spanish grupo equipped with Fiat fighters. Grupo 2-G-3 consisted of 13 aircraft and 15 pilots, which were divided into two escuadrillas of six fighters each. The final CR.32 was Morato’s personal (3-51).
Of the pilots assigned to its escuadrillas, two of them had previously served as wingmen in the Patrulla Azul, while the remaining 12 were chosen according to their experience in fighters.

Escuadrilla 1-E-3
Teniente Julio Salvador (CO)
Teniente Miguel Guerrero García
Alférez Manuel Vázquez Sagastizábal
Alférez Arístides García López Rengel
Alférez Rafael Mazarredo Trenor
Alférez Jesús Rubio Paz
Brigada Ramón Senra Àlvarez

Escuadrilla 2-E-3
Capitán Ángel Salas
Capitán Narciso Bermúdes de Castro
Capitán Javier Murcia Rubio
Teniente Miguel García Pardo
Alférez Allende Isasi
Alférez Joaquín Ansaldo Vejarano
Alférez Jorge Muntadas Claramunt

On 2 September, 2-G-3 surprised a formation of about 15 ’Chatos’ in the Belchite area, of which they destroyed seven. These victories were scored by capitán Ángel Salas Larrazábal (CO 2-E-3) and teniente Julio Salvador Díaz-Benjumea (CO 1-E-3) (two each) and by capitán Joaquín García Morato (CO 2-G-3), alférez Allende Isasi (2-E-3) and José Careaga Urigüen.
The only known Government loss in this area during the day is Emilio Herrera Aguilera, who was killed in combat during the day.

On 28 December, 16 fighters from Grupo 2-G-3 clashed with nine I-15s and 12 I-16s directly above Teruel. Nationalist pilots were credited with shooting down four ‘Curtiss fighters’ and a Rata for the loss of Antonio López Sert (3-87) of Escuadrilla 1-E-3 (reportedly to small-arms fire). Teniente Carlos Bayo Alessandri (2-E-3) attacked a Chato head-on, scoring some hits. He made a second attack from astern and the enemy fighter began to lose height and crashed behind Republican lines near Villastar. Alférez Allende Isasi (2-E-3) claimed two I-15s while alférez Jorge Muntadas Claramunt (2-E-3) claimed the fourth I-15 and alférez Manuel Vázquez Sagastizábal (1-E-3) claimed the I-16.
It seems that at least the 3^a/26 (I-15) was involved in this combat and they claimed four CR.32s during the day. The CO of the unit, teniente Juan Comas Borrás claimed two CR.32s while sargento Francisco Montagut Ferrer and Rafael Sanromá Daroca claimed one each.
The Republicans admitted the loss of teniente José M.^a Campoamor Peláez, who fell with his burning I-15 in the vicinity of La Muela, while two other aircraft returned to base damaged.

During 21 February 1938, all the serviceable Polikarpovs took off to try to oppose Nationalist bombers during the Battle of Alfambra.
At 10:20, Miguel García Pardo and Allende Isasi of 2-G-3 took off on a routine reconnaissance flight over the Teruel front. There they discovered 20 I-15s and a similar number of I-16s in combat with a few Bf 109Bs. When García Pardo and Allende Isasi went to the assistance of the Messerschmitts, the German pilots failed to recognize them as allies and opened fire on them. They beat a hasty retreat, calling into battle another formation of Fiat CR.32s before continuing with their reconnaissance.
The new formation compromised 24 CR.32s of the XXIII Gruppo ”Asso di Bastoni” led by Maggiore Andrea Zotti. The pilots included the Spanish capitán Carlos Haya González who, after attending his mother’s funeral, arrived by car in Bilbao just as the group was about to take off. Despite Commander Zotti’s opposition, he insisted on taking his place in the formation.
At 11:04 over Teruel when they spotted about 40 Republican fighters split in three formations with I-15 “Chatos” at 3,500 and 4,000 meters, and I-16 “Moscas” at 5000 meters. The Republican fighters were already in combat with 17 Bf 109s. Zotti immediately chased them, and sent part of the Gruppo to attack the “Chatos”, which tried to evade as they were over Republican lines. At Puebla de Valverde, the “Moscas” intervened, but they were faced by the rest of the XXIII Gruppo, which at the end claimed two “Chatos” and a “Mosca” destroyed. One of the I-15s was claimed by Franco Lucchini of the 19^a Squadriglia. In attempting to destroy an I-15 that was attacking another aircraft of his squadron, Carlos Haya González approached too close and collided with the I-15, falling to his death. It seems that this was sargento Francisco Viñals Guarro (I-15 CA-013) of the 2^a/26, who managed to return despite the almost total destruction of the rudder (according the Republic bulletin, it was teniente Manuel Orozoco Ovira, of the 4^a/26, who collided with Haya). Viñals’ I-15 was found to have a shattered aileron, badly damaged upper port wing and missing cockpit door and gunsight. Viñals’ promotion, recommended by the coronel Jefe de Fuerzas Aéreas and the Minister of National Defence, Indalecio Prieto, was effective from 22 February. The order was gazetted in the Diario Oficial issue No 47, which noted, ’For his heroic conduct in yesterday’s combats near Teruel, sargento del arma de aviación Francisco Viñals Guarro is promoted to teniente.’
Juan Lario Sanchez witnessed this combat. Haya fell near Puerto de Escadiòn, and was posthumously awarded with a Medaglia d’oro al valor militare.
The German pilots of J/88 claimed seven I-16s when 1 staffel claimed three near La Pueblé (Leutnants Fritz Awe, Hans-Karl Mayer and Erich Woitke) and 2 staffel claimed four near Sarrion and Teruel (Unteroffizier Herbert Ihlefeld, Leutnant Edgar Rempel, Unteroffizier Kurt Rochel and Staffelführer Oberleutnant Joachim Schlichting).
It seems that the Bf 109s had been in combat with twelve I-16s from 2^a/21, which suffered three wounded pilots and one killed in combat with Messerschmitts and Fiats over Teruel in the morning while reporting 18 enemy aircraft downed (daily total?). Leitenant Aleksey Denisov (I-16 CM-034) claimed one Bf 109 before being shot down and had to bail out wounded. Leitenant Boris Adil’gireevich Takhtarov was wounded and badly burned when his aircraft (CM-123 or CM-239) caught fire after being hit by Bf 109s and he had to take to his parachute. When he jumped his parachute opened early, and on the way down the Germans tried to strafe him, but his comrades prevented them (he spent 35 days in the hospital and then returned home). The third wounded pilot was Andrey Belov. Leitenant Viktor Sergeevich Troshkin was killed while flying CM-032.
General Rojo advised Prieto, the Minister of Defence, that the Air Force had carried out three operations during the day, and that during the last of these they had been involved in a large-scale combat with the Nationalist Air Force. He later advised Prieto that according to information from Jerica (the Air Force’s command centre) five German aircraft – later stated to be five Bf 109s, seven Fiats CR.32s and one twin-engined aircraft had been destroyed. This message included the information that the ace pilot, Carlos Haya, who was reputed to have carried out the night attack on the War Ministry in Madrid, had been killed in this engagement. Their own losses were quoted as two I-16, which failed to return to base and two others, which were damaged and whose pilots were injured. Sergeant Manuel Orozco Ovira, who managed to fly his aircraft back to base after its tail had been destroyed, was recommended an award for outstanding bravery and skill.
The I-15s from the 2^a/26 claimed three and two probable CR.32; these were claimed by Teniente Leopoldo Morquillas Rubio (CO) (1 probable), J. Mora Fauria, sargento Francisco Viñals Guarro, Fernando Villins León (1 probable) and C. Zuazo Garre. Francisco Montagut Ferrer from the 3^a/26 claimed a Bf 109 while an unknown pilot from the 4^a/26 claimed a CR.32. An unknown I-16 pilot from 1^a/21 claimed a CR.32.

Allende Isasi ended the Spanish Civil War with 7 biplane victories. He also claimed two probables.

In 1942, he served in the Spanish expeditionary squadron in Russia.

At 10:55 on 18 July 1942, he claimed a LaGG-3.

Allende Isasi ended the war with 7 biplane victories and a total of 8.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1937
2	02/09/37		1	I-15 (a)	Destroyed	CR.32		Belchite area	2-G-3
3	28/12/37		1	I-15 (b)	Destroyed	CR.32		Teruel	2-E-3
4	28/12/37		1	I-15 (b)	Destroyed	CR.32		Teruel	2-E-3
	1942
8	18/07/42	10:55	1	LaGG-3	Destroyed	Bf 109		Russia	15. (Span)/JG 51

Biplane victories: 7 destroyed.
TOTAL: 8 destroyed.
(a) 2-G-3 claimed 7 I-15s. Only known Republican loss is Emilio Herrera Aguilera KIA.
(b) Grupo 2-G-3 claimed 4 I-15s and 1 I-16 for the loss of 1 CR.32. The Republicans claimed 4 CR.32s while losing 1 I-15 and 2 damaged.

Sources:
Air Aces - Christopher Shores, 1983 Presidio Press, Greenwich, ISBN 0-89141-166-6
Air War over Spain - Jesus Salas Larrazabal, 1974 Ian Allan Ltd, Shepperton, Surrey, ISBN 0-7110-0521-4
Fiat CR.32 Aces of the Spanish Civil War - Alfredo Logoluso, 2010 Osprey Publishing, Oxford, ISBN 978-1-84603-983-6
Joaquin Garcia-Morato - Best Ace of Spanish Civil War (WWII Ace Stories) - Mihail Zhirohov, 2003
Soviet airmen in the Spanish civil war 1936-1939 - Paul Whelan, 2014 Schiffer Publishing Ltd, ISBN 978-0-7643-0
Spanish Republican Aces – Rafael A. Permuy López, 2012 Osprey Publishing, Oxford, ISBN 978-1-84908-668-4
Wings Over Spain - Emiliani Ghergo, 1997 Giorgio Apostolo Editore, Milano
Additional information kindly provided by Miguel Ansede Fernández, Alfredo Logoluso and Ondrej Repka.