In George Bernard Shaw's Arms and the Man, the battle of Slivnitza, an engagement in the Serbo-Bulgarian war of 1885, is the event that lies behind the whole action of the play. Though it takes place off-stage before and during the opening, its significance is felt throughout, for it sets the plot in motion and provides the material for Shaw's satire on war and heroism.
It sets the plot in motion. It is the rout following the battle that drives the fleeing Swiss mercenary, Captain Bluntschli, to climb through Raina's balcony window into her bedroom. This flight brings the play's central figures together and initiates the whole intrigue of hidden identity, the chocolate soldier and the divided romantic attachments.
It is the source of Sergius's false glory. The battle produced Sergius's famous cavalry charge, which made him a celebrated hero and the pride of Raina. Slivnitza is thus the foundation of the romantic reputation that the play will proceed to dismantle.
It exposes the truth about heroism. Bluntschli's eyewitness account strips the glamour from the charge. He reveals that Sergius's reckless attack should have been fatal and succeeded only by chance, because the enemy had been sent the wrong cartridges and could not fire. Slivnitza therefore becomes the concrete illustration of Shaw's thesis that battlefield "heroism" is often folly rewarded by luck.
It contrasts the romantic and the realistic soldier. The battle juxtaposes Sergius, the flamboyant amateur who charges gloriously, with Bluntschli, the seasoned professional who runs away to survive and carries chocolates rather than cartridges. Through their opposing conduct at Slivnitza, Shaw dramatises the difference between illusion and reality in war.
It advances Shaw's anti-romantic message. By anchoring his satire in a real, recent war, Shaw grounds his mockery of military glory in believable circumstance and lends weight to his argument that the truth of war is fear, chance and blundering, not the noble pageantry of romance.
In conclusion, the battle of Slivnitza is significant because it launches the plot, creates Sergius's hollow reputation, supplies the evidence that exposes false heroism, and drives home Shaw's realistic, anti-romantic view of war.