Blind Bombing: How Microwave Radar Brought the Allies to D-Day and Victory in World War II by Norman Fine

Silver Medal Winner, 2020 Independent Book Publishers (IPPY) Awards

“A riveting addition to the literature on scientific innovation during the Second World War.”
—Kirkus Reviews

On January 1, 1944, after four years of bombing Nazi Germany by the British and nearly two years of bombing by the U.S. Army Air Forces, Germany’s war-making infrastructure was still operating—manufacturing plants, railroads, fuel production. The Allies were insistent on staging D-Day that summer, but the pre-conditions for a major land invasion by sea had not yet been accomplished.

The strategic bombing campaign had failed. U.S. Air Force leaders in Europe knew that without something new, they would soon be losing their heavy bombers—B-17 Flying Fortresses and B-24 Liberators—to the Pacific theater. D-Day plans were in peril.

Yet, less than six months later, on June 6, 1944, D-Day, the day the Allies put 150,000 men on the Normandy beaches with their weapons, ammunition, trucks, and tanks, there was scarcely a German plane in the sky to oppose them. Of the few German planes still airworthy, there was no fuel to run them, no spare parts to repair them, and few experienced pilots to fly them. Most of those men had been shot down.

Considering the previous years of bombing by the RAF and the USAAF and not getting the job done, how was it finally accomplished in just six months? Microwave radar design was made possible by a new and secret British invention on the very eve of the war. The gadget was called a resonant cavity magnetron and improved radar performance a hundred-fold. Introduced into the Allied bombing campaign in January 1944, it conquered the final obstacle to D-Day, the thick European weather that allowed, on average, only seven completed bombing missions per month. Not enough!

All the combatant nations had radar, but it was primitive—too large and bulky to be usefully installed in a plane or truck. And it couldn't show detail. Only the Allies had microwave radar, and the enemy was mystified by their mounting losses.

For the five months before D-Day, microwave radar sets installed in a handful of heavy bombers led the bomber formations to their targets, “saw” the targets through the overcast, and dropped the first bombs and marker flares. The bomber formations following blindly dropped their own bombs on the marker flares. It was an act of faith since the bombers behind the leading radar plane could see nothing on the ground. Yet, in the beginning, there was precious little faith. Veteran airmen and many air force leaders despised the new protocols.

The resonant cavity magnetron turned out to be the new invention most influential in the winning of the war. It overcame the two major obstacles to D-Day: first the U-boats, then the perpetually overcast European weather. Yet scarcely anyone has ever heard of it, or of the two young physicists who invented it.

The story of microwave radar—the men who designed it and the warriors who introduced it as an offensive weapon of war—was an unprecedented cooperative effort between a small band of civilian scientists and forward-thinking air force officers who first had to overcome the apathy and resistance of their own entrenched military leadership before they could finally overcome the enemy.