The Deadly War Over A Bucket
In 1325, two Italian city-states fought a bloody war sparked by the theft of a simple wooden bucket. Thousands died in a single battle, and the disputed trophy remains on display in Modena to this day.
While the bucket was the immediate catalyst, it was really just a symbolic insult in a centuries-long feud between the pro-pope Guelphs and pro-emperor Ghibellines. After Modena won the Battle of Zappolino, they captured the bucket as a prize. The object was never returned to Bologna despite long-standing tensions. You can still visit the original wooden trophy at the bell tower in Modena centuries later.
Source: War of the Bucket