If I could choose any time to time travel I would go back to the battle between Spanish conquest and the Aztec empire. The Spanish conquest of the Aztec Empire, also known as the Conquest of Mexico or the Spanish–Mexican War (1519–21), was one of the primary events in the Spanish colonists of America. It was not solely a contest between a small contingent of Spaniards defeating the Aztec empire but rather the creation of a coalition of Spanish invaders with tributaries to the Aztecs, and most especially the Aztecs’ indigenous enemies and rivals. They combined forces to defeat the Mexica of Tenochtitlan over a two-year period. For the Spanish, the expedition to Mexico was part of a project of Spanish colonization of the New World after twenty-five years of permanent Spanish settlement and further exploration in the Caribbean.
Tenochtitlan was a large Mexican city. The exact date of the founding of the city is unclear. The date 13 March 1325, was chosen in 1925 to celebrate the 600th anniversary of the city. The city was built on an island in what was the Lake Texcoco. The city was the capital of the expanding Aztec Empire in the 15th century.
I would go gere because it is fun to go back in historic events.