Factors on the home front determined the outcome of the First World War to a considerable extent. While morale in the Allied countries was generally good, there was a collapse in morale in Germany that made it harder for their armies to keep on fighting.
For the most part, this collapse in morale was due to chronic food shortages. Germany was badly affected by the British blockade along with a series of bad harvests and a massive disruption of domestic supply chains.
Inevitably, this led to serious discontent on the home front, with more and more people coming out strongly against the War. There was even talk of mutiny among German soldiers and sailors.
Although the wretched public mood on Germany's home front was by no means the only factor that helped bring about the end of the First World War, it helped convince Germany's military leadership that the war could not continue.