Today marks the 72nd anniversary of the invasion of Normandy, France and the thousands of Americans that sacrificed everything to save the world from tyranny.

Operation Overlord, also known as D-Day, was an assault mounted by U.S., British, and Canadian forces along the northern coast of France in order to remove Adolf Hitler's foothold on Europe.

As General Dwight D. Eisenhower wrote in a letter to the invading American troops, the mission proved to be more than extraordinary:

You are about to embark upon the Great Crusade, toward which we have striven these many months. The eyes of the world are upon you. The hopes and prayers of liberty-loving people everywhere march with you... Your task will not be an easy one. Your enemy is well trained, well equipped and battle-hardened. He will fight savagely... I have full confidence in your courage, devotion to duty, and skill in battle. We will accept nothing less than full victory...

The mission started around 1:30 a.m. when 13,000 American airborne troops were dropped amongst the German 7th Army and tasked with blocking approaches into the vicinity of the amphibious landing, capturing exits off the beaches, destroying anti-aircraft weapons, and establishing crossings at the pivotal town of Carentan. Many of the airborne soldiers missed their landing zones by miles yet immediately began to form small groups to carry out their missions. Hundreds of airborne Americans died before sunrise.

On the coastline, the second phase of the operation began around 5:30 a.m. when six Allied divisions began landing on French beaches codenamed Omaha, Sword, Juno, Gold, and Utah.

The fighting continued for over two months until the the Allied forces surrounded the German army at Falaise, liberated Paris, and forced Hitler to retreat across the Seine on August 30th, marking the end of Operation Overlord.

The cost of the Normandy campaign proved to be one of the most costly in human history. From D-day through August 21, the Allies suffered more than 226,386 casualties.

Operation Overlord still remains the largest amphibious invasion in history.