The Charge up San Juan Hill refers to a pivotal military action during the Spanish-American War that took place on July 1, 1898. This battle was crucial in securing a victory for American forces in Cuba and was famously led by Theodore Roosevelt and his Rough Riders, alongside other regiments. The successful assault symbolized American military resolve and marked a turning point in the war, showcasing both the bravery of the soldiers involved and the shifting dynamics of U.S. imperial ambitions.