The 1916 Punitive Expedition was a disproportionate response to the attack by Villa and his 500 revolutionaries. With a force of 12,000 men equipped with aircraft and motorized transport General Pershing pushed over 400 miles into Mexico in pursuit of Villa. The American intervention caused an upsurge in Mexican Nationalism and prompted the interim president, Venustiano Carranzazo, to dispatch units of the Mexican federal army to engage the U.S. troops in Mexico. The American incursion into Mexico caused a flow of refugees back into the United states prompting the government to send units of the regular army units and federalized Units of the National Guard to maintain protection along the border. The authority to accomplish this was the newly legislated National Defense Act of 1916. Almost overnight the camp became a large military installation for the defense of the border with Mexico. Following the end of the Mexican Revolution in 1917 the need for a large border camp lost its importance and by 1923 all troops had been removed from the camp.