File:Flag of the German Empire.svg

Summary
Flag of the North German Confederation (1866-1871) and the German Empire (1871-1918). By User:B1mbo and User:Madden (Recoloured Image:Flag of Germany (2-3).svg) [Public domain], via Wikimedia Commons. Source available here: https://commons.wikimedia.org/wiki/File:Flag_of_the_German_Empire.svg