Where does the expression “all quiet on the Potomac” come from and What does it mean?

The expression “all quiet on the Potomac” means: Peaceful; undisturbed; a time of ease or quiet enjoyment: from the frequent repetition of the phrase in bulletins issued during the War between the States, 1861-1865.

The original expression has been ascribed to General George B. McClellan (1826-85 ), who was in command of the Army of the Potomac in 1861 and 1862, but who received much criticism in Washington because of alleged dilatory policies and lack of aggressiveness.

The phrase sometimes appears as “all quiet along the Potomac,” from the poem, “The Picket Guard” (1861), by Ethel Lynn Beers, the sixth stanza of which is,

All quiet along the Potomac tonight,
No sound save the rush of the river,
While soft falls the dew on the face of the dead,
The picket’s off duty forever.