Illustrious's eight twin 4.5-inch mountings were placed high enough to stay clear of heavy seas in the North Sea and Atlantic. Their position allowed broad arcs of fire without closing the flight deck during operations. Fighters disrupted incoming formations, heavy anti-aircraft guns broke them up further, and medium guns confronted isolated attackers. The aim was to prevent a concentrated raid from overwhelming the ship, even when every attacker could not be destroyed. Reconnaissance and spotting aircraft could also provide visual warning of approaching aircraft before radar became available.
Notable Point · 30:06-33:59
Breaking up an air attack
Fighters, heavy anti-aircraft fire, and pom-poms were designed to fragment a raid before it reached the carrier.