AFTER the evacuation of Yorktown on the fourth of May, in 1862, this picture was taken. It shows the generals of the Army of the Potomac in full uniforms after the hard siege, and at the very time when they were maneuvering to drive back the Confederates, forcing them to stand in defense of the Capital of the Confederacy--Richmond. It was through the personal friendship of Major-General McClellan that Brady was allowed to take this rare photograph. The warriors lined up in front of the camera on the field at Yorktown. In the center is General McClellan--a man in whose veins flowed the blood of Scotch cautiousness--"Be sure you're right, then go ahead!" He was but thirty-six years of age when he held the great army under his control. From boyhood he had been a military tactician. When twenty years old he was graduated from West Point, standing second in his class, and distinguished himself for gallantry in the Mexican War. Six years before the outbreak of the Civil War, when only thirty years old, McClellan was in Crimea and two years later he submitted his report to the Government and resigned from the army to become vice-president and chief engineer of the Illinois Central Railroad. In 1860, he was general superintendent of the Ohio and Mississippi Railroad. When the call swept across the continent for troops to preserve the Nation, the old war spirit was aroused and McClellan was one of the first to respond. [Illustration: PHOTOGRAPH TAKEN AT YORKTOWN OF MCCLELLAN AND HIS OFFICERS IN 1862]