On 3 September 1943, the British Eighth Army, under the command of General Bernard Montgomery, crossed the Straits of Messina from Sicily and landed in Calabria during Operation Baytown to seize the ports of Reggio and San Giovanni. The main invasion was planned for 9 September, with the U.S. Fifth Army, commanded by Lieutenant General Mark Clark, landing at Salerno on the western coast in Operation Avalanche, with Naples as their immediate objective. The Allies hoped that the invasion would persuade the Italian forces to surrender. If they did, the five Italian divisions in France and the twenty-nine in the Balkans would have to be replaced by German formations. Also, if the Germans then decided to continue the fight in Italy, they would have to redeploy some of their troops engaged on the Eastern Front or on occupation duties in France.