The invasion began shortly after midnight on the morning of 6 June with extensive aerial and naval bombardment as well as an airborne assault—the landing of 24,000 American, British, and Canadian airborne troops. The men landed under heavy fire from gun emplacements overlooking the beaches, and the shore was mined and covered with obstacles such as wooden stakes, metal tripods, and barbed wire, making the work of the beach-clearing teams difficult and dangerous. The highest number of casualties was at Omaha, with its high cliffs. At Gold, Juno, and Sword, several fortified towns were cleared in house-to-house fighting, and two major gun emplacements at Gold were disabled using specialised tanks. This operation cost the allies 10,000 casualties including 4,414 KIA. Today we remember their sacrifice - Lest We Forget.