Juin's CEF relieved Lucas's VI Corps in the line when the CEF's second division, the 3rd Algerian Infantry Division (3e DIA) arrived in December. For the CEF, the First Battle of Monte Cassino began on 12 January 1944, with the CEF advancing four miles to the upper Rapido River and the main defences of the German Gustav Line. After the Allied landings at Anzio on 22 January 1944, he began an attack on Monte Belvedere, about north of Monte Cassino. On 29 January, he reported to Clark that "At the cost of unbelievable efforts and great losses," the 3rd Algerian Infantry Division had "accomplished the mission which you gave them."