Just before twelve o'clock General Stone sent word to Colonel Baker that the force of the enemy was supposed to be about four thousand. Colonel Baker was in doubt whether to remain or whether to send over more troops; but word came to him that the Rebels were advancing, and he ordered over the Tammany Regiment of New York troops, commanded by Colonel Cogswell, and Lieutenant-Colonel Wistar's California Regiment. Colonel Baker went over about two o'clock in the afternoon. By constant effort, he succeeded in getting about seventeen hundred men over during the day, and three cannon,--two mountain howitzers and one rifled gun. It was nearly three o'clock in the afternoon before General Evans began the attack. He had captured a courier the day before, sent by General McCall to General Meade, and from the despatches learned that General McCall was only making a reconnaissance. This information led him to bring all his forces back to Leesburg, and it also delayed his attack until late in the afternoon. Captain Duff, of the Seventeenth Mississippi, was reinforced first by four companies of the Thirteenth and Eighteenth Mississippi, commanded by Colonel Jennifer. About two o'clock the Eighth Virginia arrived from Goose Creek, commanded by Colonel Huntoon. Other reinforcements were near at hand. "Drive the Yankees into the river!" was General Evans's order. He had the advantage of position, being on higher ground than that occupied by Colonel Baker. But he advanced very cautiously. Colonel Baker formed his men on the eastern border of the field in the edge of the woods. The Fifteenth Massachusetts was on the right,--next there was a portion of the Twentieth Massachusetts, which had been sent over, and then the California and Tammany regiments. The Rebels began to fire at long range. Some of them climbed into the trees,--some secreted themselves in the shocks of corn which were standing in the field,--some crouched behind the fences and trees. Colonel Baker, to save his men, ordered them to lie down. Colonel Jennifer, commanding a Rebel regiment, with a party of skirmishers, went round the north side of the field and came upon the Fifteenth Massachusetts, but the men of that regiment fired so steadily that the Rebels were forced to retire. At the southwest corner of the field was a farm road, down which the Rebels advanced. The howitzers and the cannon were placed in position to rake that road, and the Rebels were compelled to leave it and form in the woods. It was apparent to Colonel Baker and all of his command at three o'clock that the Rebels outnumbered them, but they prepared to make a brave fight. The fire from both sides began to be more fierce and rapid. At this time General Gorman had crossed the river at Edward's Ferry, three miles below, with fifteen hundred men. General Evans, to prevent a junction of the Union forces, moved his troops into a ravine, and came upon the left flank of Colonel Baker's command.