Definition of "secesh"

This is true, for Mrs. Sherman has an idea that St. Louis is unhealthy for our children, and because most of the Catholics here are tainted with the old secesh feeling.

1864, William T. Sherman, The Memoirs of General W. T. Sherman, Vol. II., Part 4‎

But he was mistaken; for as the current swept the bateau around the bend of the river, he discovered, to his astonishment and chagrin, the two secesh soldiers, who had left the picket post some time before, standing at convenient distances from each other and from the shore, in the water, ready to rescue him from the fate before him.

1864, Oliver Optic, The Soldier Boy; or, Tom Somers in the Army‎

Nearly every building was draped, no matter whether its occupants were pinched or prosperous. Even secesh families hung crepe. Sometimes, the more secesh, the more crepe. It was the same way across the country, as Sarah Morgan, a young Baton Rouge belle, wrote in her diary. "The more violently secesh and the more thankful they are for Lincoln's death, the more profusely the houses are decorated with emblems of woe."

2015, Kathryn Canavan, Lincoln's Final Hours: Conspiracy, Terror, and the Assassination of America's Greatest President, University Press of Kentucky

[…] I think they buried more secesh than our folks.Question. How did they bury them?Answer. They buried the secesh over back of the fort, all except those on Fort Hill; them they buried up on top of the hill where the gunboats shelled them.

1888, Joseph Thomas Wilson, The Black Phalanx: A History of the Negro Soldiers of the United States in the War of 1775-1812, 1861-'65, page 332

[…] our minds to get 'em, and we charged, yelling like bloody hl, drove the seceshes back a deuced sight quicker than they come, and popped 'em down at every shot.

2010, Harold Holzer, Craig Symonds, New York Times Book of the Civil War 1861-1865: 650 Eyewitness Accounts and Articles, Black Dog & Leventhal

'You don't see any grief?' Edward shouts, turning on me. 'I'd sure like to know what you're doing in an Army if you ain't keen on fighting! People are counting on us keeping those Seceshes from coming North, is what you mean.'

2014, Erin Lindsay McCabe, I Shall Be Near to You: A Novel, Broadway Books