Through what bit of historical lore does coffee eternally link Hartwood Church and Kelly's Ford ?

When 400 of Gen. Fitzhugh Lee's Confederate cavalrymen crossed the Rappahannock River on February 25, 1863, and captured 150 Union horsemen near Hartwood Church, Va., Lee left a note for Gen. William W. Averell, an old friend and commander of the captured Union soldiers: "If you won't go home, return my visit and bring me a sack of coffee

About three weeks later :"Finally, at about 5:30 P.M. Averell ordered his men to withdraw, and they crossed back over the river. The Confederates' 170 casualties were more than double the 78 men that Averell had lost. Before he crossed the Rappahannock, Averell left a sack of coffee for Lee with a note: "Dear Fitz: Here's your coffee. Here's your visit. How did you like it?"

Quite right ! The two were old friends but not above a little taunting !

Thanks for the answer !