… a 1968 Italian–Spanish Western film directed by Enzo G. Castellari. Chuck Connors headlines an ensemble cast …

The story centers around a gang of robbers, whose boss (Connors) is tasked by a Confederate captain (Wolff) with stealing gold from a Union fort, before wiping out all of his men to save on their share of the booty. The film has earned notice as one of the genre’s most action-oriented examples.

https://en.wikipedia.org/wiki/Kill_Them_All_and_Come_Back_Alone

https://www.youtube.com/watch?v=AECq-28mTDA - the link from above, blocked in Austria, Germany, Spain, France, Italy.