He belonged to that army known as invincible in peace, invisible in war.

Sherman’s line is a sardonic jab at the “armchair soldier” or peacetime braggart: people who present themselves as formidable when there is no risk, but who vanish—or prove useless—when real fighting begins. The antithesis (“invincible” vs. “invisible”) compresses a familiar military critique into a memorable epigram, implying that true courage and competence are demonstrated under pressure rather than in talk, posturing, or retrospective storytelling. In the Civil War era, such remarks also resonated with tensions between professional soldiers and civilians (or political appointees) who claimed martial authority without sharing battlefield exposure.