The Ottoman Empire fought alongside the Central Powers in World War 1, namely Germany and the Austria-Hungarian Empire. It had already been in a period of decline leading up to the war, and its defeat to the Allied Powers was essentially what led to its dissolution.
Following the defeat of the Central Powers and the occupation of Constantinople (Istanbul in present-day Turkey) that followed, the Ottoman Empire was partitioned (divided up) and temporarily administered by the victories Allied Powers. This meant the abolition of the Sultanate and the end of the Ottoman Empire.
