This thread causes me to recall the heliograph network established by the US Army during the Geronimo campaigns of the 1890s. They established outposts on prominent mountain peaks throughout southern Arizona. Heliograph peak in the Graham mountains was one such. The network focused on Ft. Bowie, where messages were sent dirctly to the parade ground in the fort. When I worked at Ft. Bowie in 1968, the post which supported the heliograph on that peak was still there.

There is still a remnant of a huge rock cairn on Rincon Peak, east of Tucson, which was part of the heliograph there. According to accounts, the helio network worked well and effectively. One source states that Geronimo knew the jig was up when he saw the system in operation.

I am not sure of this, but i believe the Apaches, and possibly other groups, used mirror flashes tactically.