The Watermelon War is a riot that occurs in the morning of April 15, 1856, in Panama City, at this time the capital of Panama State in the Republic of New Granada.

After an American is caught stealing a watermelon, a verbal conflict starts, which escalates later, resulting in robbery, brawls and shootings.

The incident comes to be recognized as a symbolic and historical allegory for frictions that accompany the relationship that builds the trans-isthmian railroad, then a transoceanic canal.