When you forget to upgrade old units in civilizations

Its a screaming frog

Damn those DLCs -.-

This reminds me of a time I was playing Civ 5 and I went to invade the Mongols. I began my advance and was warned that I would be destroyed by my planned target. As I declared war I was told of how I would be destroyed for all the world to see. My Gatling gun units slowly marched into enemy territory, not knowing what lie ahead. Their vision blocked by the fog of war and they were fearing an ambush of riflemen or attackers speeding by on horseback. Instead I was greeted by the soldiers meant to bring my death, which was a few warriors wielding axes. Needless to say I won that war fairly quickly