Help me find an old adventure movie, probably from the 1950s. I saw it on late night TV back in 1969. All I remember is one battle scene. An expedition with two cannon are crossing a shallow river. they are then attacked by natives using arrows, spears, blow guns. The main characters, two men, unlimber the cannon, and load them in the middle of the river, with the water almost up to the muzzle. they then fire off several rounds to chase of the natives. One native releases a poisoned blow dart which hits one of the men in the...