Scott began his advance toward Mexico City on April 8, 1847. The first resistance encountered was near the hamlet of Cerro Gordo where Santa Anna had strongly entrenched an army of about 12,000 men in mountain passes through which the road ran to Jalapa. Scott quickly won the battle with a flanking movement that cut off the enemy escape route, and the Mexicans surrendered in droves. From 1,000 to 1,200 casualties were suffered by the Mexicans, and Scott eventually released on parole the 3,000 who had been taken prisoners. Santa Anna and the remnants of his army fled into the mountains. American losses were 64 killed and 353 wounded. Scott quickly pushed on to Jalapa, but was forced to wait there for supplies and reinforcements. After some weeks, he advanced cautiously to Pueblo. Wounds and sickness put 3,200 men in the hospital, and the departure for home of about 3,700 volunteers (seven regiments) whose enlistments had expired left Scott with only 5,820 effective enlisted men at the end of May 1847. Scott stayed at Puebla until the beginning of August, awaiting reinforcement and the outcome of peace negotiations which were being conducted by Nicholas P. Trist, a State Department official who had accompanied the expedition. The negotiations having failed, Scott boldly struck out for Mexico City on August 7, abandoning his line of communications to the coast. By this time, reinforcements had brought his army to a strength of nearly 10,000 men. Santa Anna had disposed his army in and around Mexico City, strongly fortifying the many natural obstacles that lay in the way of the Americans.