Scott chose the Acapulco road for his route of approach, the national road being commanded by the lofty and strongly fortified hill of El Peñon, precipitous on one side, and surrounded by marshes and a deep ditch on the other. The Acapulco road was defended by strongly garrisoned fortresses at Contreras and Churubusco, but seemed more available than the other route. Still farther north and west of the capital was a third approach to it over the road to Toluco, defended by works at Molino del Rey and by the fortified hill of Chapultepec. It was evident that the army under Scott would go through some severe and sanguinary fighting before the city could be reached. It is not our purpose to describe the various engagements by which this work was accomplished. It must suffice to say that the strong hill fort of Contreras was taken by a surprise, being approached by a road leading to its rear during the night and taken by storm at sunrise, seventeen minutes sufficing for the important victory. The garrison fled in dismay, after losing heavily. An advance was made the same day on the nearby Mexican works at San Antonio and Churubusco, and with the same result. The garrison at San Antonio, fearful of being cut off by the American movement, evacuated the works and retired upon Churubusco, hotly pursued. The Americans, inspired by success, carried all before them, taking the works at the bridge of Churubusco by an impetuous charge and soon putting the enemy to flight. Meanwhile, General Shields attacked the Mexican reserve, consisting of four thousand infantry and three thousand cavalry, whose line was broken by a bayonet charge. The whole Mexican force was, by these well-devised movements, forced back in terrible confusion, and was quickly fleeing in panic. The fugitives were cut down by the pursuing Americans, who followed to the immediate defences of the capital, where the pursuit was checked by a heavy fire of grape-shot. Thus in one day the Americans, nine thousand strong, had captured three strong positions, held by three times their number, the Mexicans losing in killed, wounded, and prisoners over six thousand men, while the American loss in killed and wounded was less than a thousand. Negotiations for peace followed, but they came to nothing, the armistice that had been declared terminating on the 7th of September. The problem that now lay before General Scott was a very different one from that which Cortez had faced in his siege of the city. In his day Mexico was built on an island in the centre of a large lake, which was crossed by a number of causeways, broken at intervals by canals whose bridges could be removed.