Peter Graves (of Mission Impossible fame) leads a cast of unknowns in this largely forgotten spaghetti western.
The Five Man Army
(1969)

A man known only as the dutchman is recruiting a small group with special talents for a difficult heist in Mexico.  The 4 men who join him know only that they will get $1000 each.  Their first task is to rescue an unimpressive looking peasant from a firing squad.  This peasant is actually a high ranking officer in the rebellion.  He knows of a train that will be carrying a fortune in gold that is being sent by European allies to aid the Mexican government.  Their job is to rob the heavily guarded train so the rebellion gets the money.

The convoluted and intricate plan goes off well, and they get the gold.  They get to their hideout to divide up the gold.  The 4 train robbers all care nothing for the revolution, and understood that they were dividing the gold among the five of them.  The dutchman surprises the others by pulling a gun on them and locking them up.  He says he is now a true believer in the revolution and is going to give all the gold to them.  The others imply that they do not believe him, and think he is keeping it for himself.

Just as dutchman is leaving with the gold a detachment of soldiers enter.  They are too many for him to face alone, and he must free the other 4 train robbers.  After eliminating the soldiers, there is a tense standoff between dutchman and the other train robbers.  As they face off, the area is surrounded by a huge force of rebel peasant troops.  The men have no choice but to give them the gold and settle for their $1000 fee. 
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Thanks Joseph C!