the two Mexican generals, that gallant officer did not hesitate to draw up his brigade in order of battle.  So broken was the ground that Santa Anna could not see the amount of force opposed to him, and declined the combat.  This was all Cadwallader wanted.  Shields’s brigade was advancing through the Pedregal, and the troops which had already crossed were rapidly moving to the rear of Valencia’s camp.  Night too was close at hand.  When it fell, Smith’s, Riley’s, and Cadwallader’s commands had gained the point they sought.  Shields joined them at ten o’clock; and at midnight Captain Lee crossed the Pedregal, with a message from General Smith to General Scott, to say that he would begin the attack at daybreak next morning.

It rained all night and the men lay in the mud without fires.  At three in the morning (August 20th) the word was passed to march.  Such pitchy darkness covered the face of the plain that Smith ordered every man to touch his front file as he marched.  Now and then a flash of lightning lighted the narrow ravine; occasionally a straggling moonbeam pierced the clouds and shed an uncertain glimmer on the heights; but these flitting guides served only to make the darkness seem darker.  The soldiers groped their way, stumbling over stones and brushwood, and did not gain the rear of the camp till day broke.  Then Riley bade his men look to the priming of their guns, and reload those which the rain had wet.  With the first ray of daylight the firing had begun again between the Mexican camp and Ransom’s corps stationed in front and Shields’s brigade at San Jeronimo.  Almost at the same moment Riley began to ascend the height in the rear.  Before he reached the crest, his engineers, who had gone forward to reconnoitre, came running back to say that his advance had been detected, that two guns were being pointed against him, and a body of infantry were sallying from the camp, The news braced the men’s nerves.  They gained the ridge, and stood a tremendous volley from the Mexicans without flinching.  Hanson of the Seventh—­a gallant officer and an excellent man—­was shot down with many others; but the Mexicans had done their worst.

With steady aim the volley was returned; and ere the smoke rose a cheer rang through the ravine, and Riley fell with a swoop on the intrenchments.  With bayonet and butt of musket, the Second and Seventh drove the enemy from his guns, leaping into his camp and slaughtering all before them.  Up rushed Smith’s own brigade on the left, driving a party of Mexicans before them, and charging with the bayonet straight at Torrejon’s cavalry, which was drawn up in order of battle.  Defeat was marked on their faces.  Valencia was nowhere to be found.  Salas strove vainly to rouse his men to defend themselves with energy; Torrejon’s horse, smitten with panic, broke and fled at the advance of our infantry.  Riley hurled the Mexicans from their camp after a struggle of a quarter of an hour; and as they rushed down the