On July 1, a combined force of about 15,000 American troops in regular infantry and cavalry regiments, including all four of the army's "Colored" Buffalo soldier regiments, and volunteer regiments, among them Roosevelt and his "Rough Riders", the 71st New York, the 2nd Massachusetts Infantry, and 1st North Carolina, and rebel Cuban forces attacked 1,270 entrenched Spaniards in dangerous Civil War-style frontal assaults at the Battle of El Caney and Battle of San Juan Hill outside of Santiago. More than 200 U.S. soldiers were killed and close to 1,200 wounded in the fighting, thanks to the high rate of fire the Spanish put down range at the Americans. Supporting fire by Gatling guns was critical to the success of the assault. Cervera decided to escape Santiago two days later. First Lieutenant John J. Pershing, nicknamed "Black Jack", oversaw the 10th Cavalry Unit during the war. Pershing and his unit fought in the Battle of San Juan Hill. Pershing was cited for his gallantry during the battle.