Operation Sealion
Leo McKinstry reveals Britain’s clandestine preparations to repel a German invasion and the reasons Operation Sealion never sailed.
- Author
- Leo McKinstry
- Publisher
- John Murray
- Price
- £25
- ISBN
- 9781848546981
- Published
- 2017
Operation Sealion by Leo McKinstry
“Sealion” was the German codename for the planned invasion of Great Britain. McKinstry’s meticulously researched account shows just how close the prospect felt in 1940 and why it ultimately faded. Drawing on newly released archives, he reveals that the British Resistance Organisation was already in place before war was declared—well trained, well supplied and quietly recruiting soldiers, farmers, fishermen, ghillies, poachers, doctors, priests and nurses to fight on after an invasion.
Britain’s defensive planning, usually shrouded in secrecy, is laid bare: hidden communication posts, buried hides, medical shelters and supply dumps were scattered across the countryside, many still visible today. McKinstry balances the celebrated Battle of Britain narrative with the efforts of Bomber Command, which pounded troop concentrations in continental ports while hundreds of thousands of Local Defence Volunteers mobilised at home. Within 24 hours of the call on 14 May 1940, more than 250,000 men had volunteered; by July the number had grown past 1.5 million and fresh weapons began arriving from the United States.
The book follows the frantic search for intelligence on where an invasion might be launched—first Norway, then Ireland—and the government turmoil it caused. Churchill swiftly removed ministers willing to consider a negotiated peace, while the Royal Family refused evacuation, prompting the preparation of multiple safe locations including Newby Hall near Ripon. Small arms training for the King and Churchill underlined how seriously the threat was taken.
McKinstry recounts an American reporter’s briefing in Berlin, where he warned German generals that Britain’s terrain, armament and determination made the island a formidable target. German plans were quietly revised to an incremental occupation halting on a Wash-to-Severn line. Yet fundamental problems proved insurmountable: losses in the Low Countries, a shortage of airborne troops and aircraft to carry them, an acute lack of landing craft and, above all, Royal Navy control of the Channel and North Sea.
Post-war interviews with German officers confirm Hitler knew the odds were stacked against him. Operation Sealion was eventually shelved, but the preparations left a legacy of ingenuity and resolve. McKinstry’s narrative captures both the hidden infrastructure and the national spirit that made invasion impossible, making this a vivid and essential read on Britain’s home front defence.
ISBN 9781848546981. John Murray. £25.