Alfonsi served as a volunteered in the Spanish Civil War in the XVI Gruppo.

On 15 November, Tenente Giuseppe Cenni, Bernardino Serafini ("Del Pelo") and Alfonsi claimed a shared probable I-16 over Madrid.

Alfonsi ended the war with one shared probably destroyed biplane victory.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1936
	15/11/36		1/3	I-16	Shared probable	Fiat CR.32		Madrid	XVI Gruppo

Biplane victories: 1 shared probably destroyed.
TOTAL: 1 shared probably destroyed.

Sources:
Giuseppe Cenni, pilota in guerra – Giuseppe Pesce, 2002, USSMA, Rome, kindly provided by Stefano Lazzaro.
Additional information kindly provided by Stefano Lazzaro and Giovanni Massimello.