What is the theme in War Is Kind by Stephen Crane?

Another symbol is patriotism. War is Kind" implicitly questions the usefulness and validity of patriotism as an attitude and an ideology. The flag, an emblem of national pride which the speaker calls "the unexplained glory," flies above the soldiers marching to their deaths on the battlefield. Its "unexplainedness" points to the speaker's belief that it cannot be explained because there is nothing rational about men fighting and dying for a symbol.