The Battle of Irún was the critical battle during the First Carlist War. From the beginning of the war, the city was a Carlist stronghold and remained in their hands until May 18, 1837, when the British Foreign Legion led by Lieutenant-General George de Lacy Evans and supported by the auxiliary forces assaulted and captured the city on the same day.
Fetching the article from Wikipedia…
Text from the Wikipedia article “Battle of Irun”, available under CC BY-SA 4.0.