15 November 1936,
First fight by the Basque Army. The Bous Mistral and Euzkal-Erria were much smaller in size than the Franco naval destroyer Velasco. The warriors shot Velasco and caused him some breakdowns. However, they beat Mistral and, with two wounded, the boats departed.
Source:
Juan Pardo San Gil, Euzkadi Army (1936-39)