This chapter covers mutinies which occur during the most dangerous times for the establishment: under conditions of war. Theoretically, any collective dissent from a legal order in a military organization is mutiny, and the events over Christmas 1914 along the Western Front in France and Belgium precisely capture this tension, with some calling it a ‘truce’ and others categorically calling it a mutiny—thus ensuring it is not repeated the following Christmas. Next we consider the Russian mutiny of 1917 that, unlike the Potemkin mutiny, occurs in a febrile national context with significant support from the political left. Some of the reverberations of Russia end up in France in 1917, straight after the failed Nivelle offensive, and this also reveals the significance of dashed expectations, as well as the dire consequences of the French state’s response. Within a year the German Navy is convulsed by similar issues, the first time it is crushed because the conditions are inadequate, but the second time, in 1918, against the backdrop of a military catastrophe and political turmoil, it is the mutiny of the German sailors that leads to the toppling of the German state. For the British and Commonwealth armies in France, post 1914, mutinies are rare, but they do occur, and it is serendipity that lends at hand. However, the largest of all British mutinies in wartime occurs in Salerno in 1943, and ironically it is stimulated by loyalty to the regiment, rather than disloyalty to the state.