Midsummer of 1863 brought a turn in the tide of military affairs.  It came none too soon for the safety of the nation.  The repeated reverses to the Union arms ending with the shocking disasters at Fredericksburg and Chancellorsville—­although slightly relieved by the costly success of Stone River—­had seemed to throw the chances of war in favor of the South; and the Union cause was at the crisis of its fate.  But now fortune smiled upon the North, and its lost hope and lost ground were regained at Gettysburg and Vicksburg.  These great battles are justly regarded as marking the turning-point of the war.  It was yet far from finished; there remained nearly two years of desperate fighting, with heroic struggles and terrible sacrifice of life, before the end should come.  But from this time the character of the struggle seemed to change.  The armies of the South fought, not less desperately, but more on the defensive; and their final overthrow was in all human probability chiefly a question of time.

Emboldened by his success at Chancellorsville in May, General Lee again assumed the offensive, and recrossed the Potomac river into Maryland.  Late in June he invaded Pennsylvania, and occupied a position threatening Philadelphia, Baltimore, and Washington.  The situation was most critical.  If Lee could once more beat the Army of the Potomac, as he had done so many times, these three great cities, and even New York, might be at his mercy.  The feeling in Washington is reflected in entries made at the time in Mr. Welles’s Diary.  “Something of a panic pervades the city,” says Mr. Welles.  “Singular rumors reach us of Rebel advances into Maryland.  It is said they have reached Hagerstown, and some of them have penetrated as far as Chambersburg in Pennsylvania....  The city is full of strange, wild rumors of Rebel raids in the vicinity and of trains seized in sight of the Capital.  The War Department is wholly unprepared for an irruption here, and J.E.B.  Stuart might have dashed into the city to-day [June 28] with impunity....  I have a panic telegraph from Governor Curtin of Pennsylvania, who is excitable and easily alarmed, entreating that guns and gunners may be sent from the Navy Yard at Philadelphia to Harrisburg without delay....  I went again, at a late hour, to the War Department, but could get no facts or intelligence from the Secretary.  All was vague, opaque, thick darkness.  I really think Stanton is no better posted than myself, and from what Stanton says am afraid Hooker does not comprehend Lee’s intentions nor know how to counteract them.  It looks to me as if Lee was putting forth his whole energy and force in one great and desperate struggle which shall be decisive.”