In September 1937, sargento Miguel Castillo belonged to the the Escuadrilla de Chatos del Norte, which operated I-15s on the Northern Front.

On 30 September, Leutnant Erich Woitke of 1.J/88 (Bf 109B) took on eight enemy fighters over Gijón. He claimed an I-16, while Feldwebel Norbert Flegel (2.J/88) claimed an unconfirmed Chato.
It seems that the German fighters had been involved in combat with the fighters from Escuadrilla de Caza del Norte where teniente Ladislao Duarte Espés (CO) distinguished himself in combat over Gijón with five Bf 109s, the operations record book entry for the day noting:

“At 1330 hrs three biplanes and three monoplanes were scrambled when seven enemy twin-engined aircraft and ten fighters were reported over Gijón. A combat ensued, and one of our monoplane fighters was shot down. It was flown by sargento Daniel Ranz [Daniel Ranz y Diez de Artazcoz], who was killed. His aircraft was a write-off. The bombers attacked the airfields at Carreño and Vega without result. The escuadrilla CO, teniente piloto Ladislao Duarte, and sargento Castillo engaged five monoplanes and deserve praise for their remarkable feat. Their aircraft landed safely although sargento Castillo’s was severely damaged.”

On 18 October, teniente Ladislao Duarte Espés, CO of the Escuadrilla de Caza del Norte, led his fighters on patrol over Gijón. The government fighters engaged Bf 109s and He 111s in a battle that lasted 1 hr 20 min. The I-15 of sargento Castillo was shot down into the sea near the port, but the aircraft had enough buoyancy to enable the pilot to escape from his cockpit and sit on the tail until he was rescued.
The pilots led by Duarte claimed to have shot down two Bf 109s and a He 111.
This was Duarte’s last combat over the north and he left the front two days later and, travelling via Biarritz and Toulouse, was held in France for several days.

In January 1939, Miguel Castillo Puerta served in the 4^a/26, which was equipped with the Polikarpov I-15.

On 21 January, he claimed a Bf 109.

Castillo ended the Spanish Civil War with 1 biplane victory.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1939
1	21/01/39		1	Bf 109	Destroyed	I-15			4a/26

Biplane victories: 1 destroyed.
TOTAL: 1 destroyed.

Sources:
Aces of the Legion Condor – Robert Forsyth, 2011 Osprey Publishing, Oxford, ISBN 978-1-84908-347-8
Spanish Republican Aces – Rafael A Permuy López, 2012 Osprey Publishing, Oxford, ISBN 978-1-84908-668-4