 Otway launched the assault as soon as the first glider <unk> the battery , ordering the explosives to be detonated to form two paths through the outer perimeter through which the paratroopers attacked . The defenders were alerted by the explosions , and opened fire , inflicting heavy casualties ; only four attackers survived to reach <unk> Four , which they disabled by firing into <unk> and throwing grenades into air <unk> . The other casemates were cleared with fragmentation and white phosphorus grenades , as the crews had neglected to lock the doors leading into the battery . During the bombing raid , the battery 's guns had been moved inside the casemates and the steel doors left open for ventilation . During the battle , 22 Germans were killed and a similar number made prisoners of war . The rest of the garrison escaped undetected by hiding in the underground bunkers . 
