The question seems to be about a historical military clash between Mexico and the United States, potentially referring to Pancho Villa's 1916 attack on Columbus, New Mexico or the Mexican-American War that began in 1846. Specific events such as these are key parts of the history between the two nations.
- The context of the question seems to be seeking information about a historical conflict between Mexico and the United States.
- No specific '200,000 men unique Cal reunion' is recorded in historical texts, but we can infer that this may refer to one of the invasions or conflicts involving the two nations.
- A significant historical event that involved a military clash between Mexico and the United States was the attack on Columbus, New Mexico, by Pancho Villa and his forces in March 1916.
- This attack led to the deaths of over a dozen US soldiers and civilians and resulted in the United States sending troops into Mexico to pursue Villa.
- Another notable conflict was the Mexican-American War, starting in 1846, after a US force encountered a Mexican cavalry unit, resulting in casualties on the US side and President Polk's declaration of war on Mexico.
- Throughout the war, several battles occurred, including the infamous Battle of the Alamo and the invasion of Mexican territory by the US.