This July 24th marks the 65th anniversary of the German retreat from Brittany and Normandy just a month and a half after the D-Day invasion of World War II. Heralded as the major turning point on the European front, the Allied invasion of Normandy remains one of the most celebrated military operations in living memory, having helped put an end to what is commonly known in America as the “Good War.”

While buzzwords like D-Day, Allied Forces, and Good War give WWII an honored place in American culture, they can also obscure the fact that this war remains the most gruesome conflict in all of human history – and one in which Americans initially fought tooth-and-nail not to get involved. So before you saunter confidently into your next US history exam, consider using the following facts to enhance your personal study guides.

In the summer of 1940 – nearly a year after WWII started with the German conquest of Poland – only 21% of Americans polled said that they weren’t outright opposed to entering the war. (Compare that to the roughly 75% of Americans polled who supported the Korean war in 1950, the Vietnam War in 1965, or the Iraq war in 2003.) American sentiments against intervention were so steadfast that in 1941, President Roosevelt was forced to wage an undeclared and arguably illegal naval war against German subs in the North Atlantic; only by claiming that the Pan-American Security Zone somehow stretched all the way to Iceland could he bypass the otherwise strict laws against this type of involvement.

In addition to its reluctance to enter into WWII, America demonstrated little interest in accommodating the Jews, Slavs, Roma, and other ethnic and minority groups targeted during the Holocaust. While some few thousands seeking asylum – including Albert Einstein – were lucky enough to gain admittance to the US, many thousands more – including Ann Frank’s family – were waitlisted in accordance with the nation’s restrictive immigration quotas. And although America’s initial disinterest can partly be attributed to a general lack of knowledge about the Nazis’ activities, the US State Department eventually did receive a cable detailing the plans for genocide in August of 1942 – and nevertheless decided to keep the intelligence a secret. Over the duration of the Holocaust, an estimated 11 to 17 thousand people, including 6 million Jews, perished in slave-labor and concentration camps.

After the Japanese bombing of Pearl Harbor finally catapulted America into the fray, over a million African-Americans reported for duty. Since their sacrifice was not considered on-par with that of their white counterparts, black servicemen were frequently relegated to menial positions that segregated them from other soldiers. In fact, Nazi POWs were often allowed to dine with white US soldiers from whose company blacks were excluded. This sad state of American civil rights prompted some blacks to defy the draft board by using racial stereotypes to their advantage. Malcolm X, for example, enthusiastically expressed a desire to “kill some crackers” in order to be disqualified from a war in which he did not feel morally obliged to participate.

Most astonishing of all is the fact that of the approximately fifty million people who were killed during World War II, about 20 million were classified as noncombatants – even though both sides agreed not to target civilians in 1939. After the repeated bombings of thriving cities like Tokyo, Dresden, and London, the atomic bombings of Hiroshima and Nagasaki in 1945 became very representative of the Allies’ so-called “tarnished victory” at the end of an unprecedentedly devastating conflict.

Considering that WWII happened less than 70 years ago, it is remarkable to think how many facts have already been overlooked. If any of them came as a surprise to you, make sure to pick up a study guide on your way out.