June 6 marks D-Day, the 1944 Allied invasion of Normandy that stunned the Germans and changed the fate of World War II.
What most people don’t know is that D-Day was supposed to happen on June 5. But a storm emerged that day in the notoriously volatile English Channel that would have made any amphibious landing a disaster.
The success of the entire operation hinged on the ability to predict the weather — using UC research.
How an operation years in the making almost sunk
Walter Munk, who became known as the “Einstein of the Oceans,” helped invent a scientific field that would prove essential to the Allies.
In the new movie “Pressure,” General Dwight D. Eisenhower (Brendan Fraser) describes how the Allied forces are mobilizing for D-Day — with more than 150,000 men, 11,000 aircraft, and 6,000 vessels — in an unprecedented effort to make a decisive strike and determine the outcome of World War II. The atmosphere is tense, and the room is filled with generals building on years of work, modeling every possible outcome to get the invasion right.
Extensive preparations, including dummy parachutists, were ready to befuddle the Germans, who by late June would be expecting the Allies.
“Only one imponderable remains,” Eisenhower remarks of the possibility of a storm in the film. They couldn’t control the weather, of course, but the emerging field of forecasting could help.
The forecasters, however, were at odds. General Eisenhower’s own trusted meteorologist predicted, based on historical patterns, that June 5 would be a fine day to invade.
But more sophisticated science cast doubt on this assessment, a key element of which was being developed at the University of California.
The scientific model that helped save the war
The Allies had been here before. Prior to D-Day, there was Operation Torch, an attempt to get a foothold in North Africa and change the fate of a losing war.
But that, too, was nearly a failure. Watching the waves as a soldier practicing landings in North Carolina, Walter Munk, the eventual legendary UC San Diego professor, saw how the landing craft often struggled if the waves exceeded five feet.
A commander suggested the Allies must have thought of that already for the nascent operation, but Munk knew the state of wave prediction science, a field just coming into its own during this war. Munk called his mentor, Harald Sverdrup, the director of UC’s Scripps Institution of Oceanography, the first oceanographic center in the United States and an early and important partner with the federal government during World War II. The pair got to work on predicting the waves.
What they developed was the world’s very first reliable, systematic approach to wave prediction. It got its first test during Operation Torch in 1942, which turned out to be a success when they helped find a window where the boats could land.
Following Operation Torch, Munk and Sverdrup were tasked by the federal government with opening a school for meteorological officers from both the Army and Navy. A team led by two of those officers used their model to inform the D-Day forecast and correctly predicted that the waves troops would face taking the beach in Normandy on June 6 would be high but manageable.
That wasn’t a risk the Nazis thought the Allies would be willing to take — but they did.
The Munk-Sverdrup model went on to inform other decisive operations, including Iwo Jima. Thousands of World War II veterans survived the war because of Svedrup and Munk.
Conditions on D-Day weren’t perfect. In “Pressure,” Allied soldiers face Nazi gunfire as they storm the beach, struggling through the waves. In headquarters, there is silence. But the soldiers break through.
The Allies would win the war, and General Eisenhower would become president. Years later, alongside President John F. Kennedy Jr. on his way to his own inauguration, Eisenhower would be asked by the incoming Commander in Chief what made the difference on D-Day.
“We had better meteorologists,” he said.
It was research that helped shape the fate of the world — another example of how UC has shaped America’s history and is powering its future.
Read more about Walter Munk and Harald Sverdrup at Scripps Institution of Oceanography (today part of UC San Diego) here.
