Even as many of its institutional legacies endured, the First World War brought about the collapse of the German colonial empire. The July Crisis of 1914 was triggered by mounting tensions in the Balkans, but colonial rivalries and the naval arms race had already helped to entrench some of the alignments that defined the war. Germany’s bid to construct Mittelafrika and to challenge Britain at sea failed. Most German colonies were conquered early with only Lettow-Vorbeck’s campaign in East Africa continued until 1918. Germany’s war aims combined continental annexations with overseas expansion, but these ambitions collapsed with the military defeat on the Western Front, creating the conditions for the November Revolution. For Germany, the Treaty of Versailles brought a double loss of empire with the cession of its European borderlands and the transformation of its colonies into League of Nations mandates. Reduced to its national core, the Weimar Republic codified a more centralised nation-state, consolidating institutional developments fostered by the colonial empire in preceding decades. At the same time, the loss of imperial status fuelled a politics of resentment that contributed to the erosion of the republican order.