The specific body of water in which Poon Lim survived his ordeal was, in November 1942, among the most dangerous in the world. The Battle of the Atlantic — the sustained campaign between German U-boats and Allied convoy protection forces that constituted one of the longest continuous military operations of the Second World War — had been ongoing since September 1939. By late 1942, it was approaching what German naval strategists called the “happy time” for their submarine fleet: a period in which U-boat operations were extracting extraordinary losses from Allied merchant shipping.
The statistics of the Atlantic campaign in 1942 are worth pausing on, because they provide the context in which the individual story of the Benlomond’s sinking must be understood. Allied shipping losses in 1942 totaled approximately 1,570 vessels sunk, representing over seven million gross tons of shipping. In the first half of the year alone, U-boats were sinking ships at a rate that threatened to outstrip Allied capacity to replace them. The Western Approaches, the Caribbean, and increasingly the South Atlantic were zones of intense submarine activity.
U-172’s third patrol, which ended with the sinking of the Benlomond and multiple other vessels, was part of this campaign. The boat had departed Lorient in August 1942 and operated in the South Atlantic — a region that had become more important to German strategy as Allied convoy protection in the North Atlantic improved. Carl Emmermann’s boat was hunting the unescorted merchant traffic on routes that crossed the equatorial Atlantic: slower ships, traveling alone, on routes where escort coverage was thinner.