A dispute in 1859 between the USA and the UK over the US-British Border in the san Juan Islands is often referred to as the “Pig War”. The confrontation is said to have started over the shooting of a pig.
There are a number of wars in Africa that were triggered by the shooting of a pig, so it’s hard to say definitively which one is right. One was in Chad- there was an outside military faction who came and shot some pigs, but they got away from their base and everyone wound up fighting about land boundaries and stuff. Another happened on the border between Botswana and Zimbabwe when war erupted over those two countries who had been fighting for years because of a boundary dispute that arose from where exactly to set the border lines due to different conceptions about territory. The exact war wouldn’t have broken out if they hadn’t started shooting pigs over it.