Why did Germany sign an armistice in 1918?

Germany signed an armistice in 1918 primarily due to the combination of military defeats on the Western Front, where Allied forces had gained significant ground, and the internal turmoil within Germany, including widespread unrest and revolution. The deteriorating economic conditions and the exhaustion of resources also contributed to the decision to cease hostilities. Additionally, the realization that continued fighting would likely lead to even harsher terms from the Allies prompted German leaders to seek an end to the war.