Early form of the Swiss flag, used as a field sign by troops under confederate command from ca. the 1470s. This was replaced by various flammé designs during the 17th century, but this older design was taken as the basis for the modern flag of 1815.
Drawn after the earliest depiction of the field sign, in the Lucerne Chronicle of 1513, in the scene showing the battle of Nancy (1477), see File:Deutsche Geschichte5-290.jpg.

A triangular version of the flag saw slightly earlier use, possibly from the 1420s, see File:Ch-1422a.png, and File:St. Jakob Tschachtlan.jpg for a 1470 depiction of the triangular flag in a scene of 1444.
Own work
Dbachmann