Complex sentence: Many hundreds of thousands of German soldiers were captured or surrendered; this, coupled with a revolution in Germany, led their generals to request an armistice which came into force at 11 o'clock on November 11,1918.
Split into simpler sentences: Many hundreds of thousands of German soldiers were captured or surrendered. This, coupled with a revolution in Germany, led their generals to request an armistice, which came into effect at 11 o'clock on November 11,1918.