For this, I'm lumping together all covert operations. Assassinations, spying, misinformation, sabotage etc. Spying and misinformation goes back farther than written history, so the first historical account goes back to 1274 BC. The "Battle of Kadesh" between the Egyptian Empire and the Hittite Empire. Muwatalli, leader of the Hittites sent a bunch of spies to the Egyptian camp posing as deserters. Two of them were able to get an audience with the Pharaoh and convince him that the HIttites were far away and they could make significant gains in territory, Of course this was a trap as they were waiting to ambush them. Fortunately for Ramses, his forces captured two more spies and interrogated them until they revealed the ambush and Ramses was able to save most of his forces. The Ra division got fucking hammered, but the rest of his army prepared for the fight to come and the Egyptians technically won, although it was strategically indecisive. It ended with a peace treaty, but had it not been for the spys there could have been some very different outcomes. Pic is of a common tactic used, a woman assassin. Because who would suspect her and she can hide some pretty decent weapons in that dress.