Looking for a movie title. 60's comedy about a mexican army disguised as a marching band in an attempt to capture a ancient fort (alamo?).

War Wagon or Paint your wagon?

Viva Max (1969)

When his girlfriend tells him that his men wouldn't follow him to a house of ill repute, Max, a general in the Mexican army decides to perform some great act of heroism. He takes his men over the border into Texas and re-captures the Alamo. This upsets the Texans greatly. The Texas National Guard is sent to retake the mission. Normally this would be easy as Max's men have left all of their ammunition back in Mexico, but the State department insists that no one be killed and so the National Guard also goes in with unloaded weapons