September 1939–June 1940
The ocean lifeline goes to war
The sinking of Athenia on the first day of the war underscores the danger to merchant crews. Britain and Canada restore escorted convoys immediately: slow SC and faster HX routes concentrate shipping so scarce escorts can protect it. The system measures success by cargo arriving, not submarines destroyed.
WHAT TO NOTICEThe campaign's central formation is the convoy: merchant ships, escorts, aircraft, ports, and routing staffs working as one system.