Engineers Save the World--June 6, 1944

Friday marks the 70^th anniversary of D-Day, June 6, 1944. It would be thoughtless to not mention the bravery of the American (and British and Canadian) men who made the ultimate sacrifice for the sake of the world during a pre-dawn operation on the French coastline. Memorial Day was last week here in the United States, but the Greatest Generation deserves its own commemoration.

The fighting men on the front lines provided the heroics and willpower that ultimately would lead to Hitler's downfall, but as with any military operation, a sizeable team of engineers and scientists provided the technical support that would lead an army ashore, and in this case fuel it to victory less than a year later.

So let's take a peek at some of the forgotten contributions to the machines, structures, and systems that wrestled Europe away from the Axis.

Mulberry harbors

Once the D-Day invasion had established a beachhead, a ludicrous amount of troops and supplies had to land to support the push through occupied France. The problem was that any harbor that could support large freighters was still held by the Germans. The Corps of Royal Engineers conducted a test of three jetty designs on the English coast that were prefabricated, modular, and robust enough to withstand the considerable loads and weather conditions expected at Normandy Beach. However, a severe storm washed away two of the three experiments before the test were completed, leaving Major Allan Beckett's design the de facto winner.

To construct these, a series of caissons were sunk parallel to Normandy Beach and rigid roadways were constructed between them. Floating pontoons measuring 80 ft. long brought vehicles, troops, and supplies ashore. These floating sections were flexible and adapted to tide and wave patterns. After 10 months of service-though originally expected to last just 3 months-the Mulberry harbor at Arromanches had landed 2.5 million troops, 500,000 vehicles, and 4 million tons of supplies. The pontoon sections, known as whales, were so strong they were later used as temporary fixes for some of France's destroyed bridges, and a few of them remain today. The ruins of the Mulberry harbor has protected historical status in France today.

"The Most Important Weather Forecast Ever"

General Eisenhower required a full moon, low tide, low swells, limited cloud cover, and light winds to have an optimal chance of taking the Normandy defenses. But an unusual seasonal weather pattern had doused the English Channel with days of storms and rain; on June 4, 1944, convoys and ships were called back from the first invasion attempt as conditions worsened. The Germany Navy had lost influence in the Atlantic, and as a result had less accurate weather forecasts. German meteorologists predicted a week of rain and rough seas, so the commanders granted passes and free time, leaving the front line with a minimal garrison.

But two teams of English scientists and one American forecaster conferred and recognized a potential break in the weather-enough of one to prompt an argument amongst themselves. Swells would be high and clouds numerous, but it was sufficient for an invasion. Eisenhower gave the go-ahead, and some estimates say the detailed forecast saved up to 60,000 lives on D-Day.

Flying, floating tanks

While it was easy (logistically, at least) to land personnel on Normandy, it was more difficult to supply infantry with the firepower needed to get through the German barricades. Tanks were an absolute requirement, but the flat-bottomed Higgins boats that brought men were ineffective. So engineers conceived two ways to mobilize the big guns.

The first way was to fly light tanks behind enemy lines, where their speed and agility could assault targets and hold them until reinforced. Thirty British light tanks, known as Tetrarchs, were loaded into the hold of gliders and towed towards Normandy along with their crew in the late afternoon of June 6. While these were meant to spearhead the invasion, they actually hindered D-Day operations more than they helped. Germans had erected many glider poles in the area to prevent stealth landings, and paratroopers had to remove them from "hot" landing zones. Considerable time had been spent making a heavy-duty glider to carry a tank into battle, but the gliders handled terribly due to the extreme weight; several of them crashed without taking fire. Finally, the Tetrarchs that made it to action were severely outgunned by German tanks in the area, and they frequently became entangled in parachute lines from personnel and the gliders.

The second way was to float tanks in from the ocean and land them on the beach, side-by-side with the infantry. Although under development since WWI, floating tanks did not see battle until D-Day. Engineers continually struggled with providing enough buoyancy, and most solutions were so impractical they were immediately scrapped. However, Nicholas Straussler demonstrated that a collapsible, waterproof screen around the tank perimeter could make a Tetrarch buoyant, and this concept was eventually applied to British Valentine and American Sherman tanks, which were also outfitted with a propeller. On D-Day, these tanks were mostly successful, but 27 of 29 floating tanks sank off Omaha Beach, most of them within minutes. Along this section of Normandy, waves were six times the height of the screens. However, floating tanks on Utah, Juno, Gold, and Sword beaches fared much better. By the time the American invaded Okinawa less than a year later, the screens had been replaced with pontoons which made the tanks infinitely more seaworthy.

All in all, the Allied victory in World War II was a team effort, but it was the skilled analytics of key engineers and scientists that liberated Europe of Nazi powers.