The movie opens with Boy (Johnny Sheffield) having fine ole time wandering around the jungle with Cheetah and a baby elephant. With Tarzan (Johnny Weissmuller) being off on a trip to the coast to retrieve a letter from the absent Jane this is a perfect time to get into trouble, so he decides to take a closer look at the lost city of Palandria, and soon finds himself hanging off a branch stuck precariously out of a high cliff face. Lucky for him Princess Zandra (Frances Gifford) of Palandria just happened to be close by, and is able to rescue him. But soon the two find themselves both needing to be rescued by Tarzan, who had just so happened to be returning from getting the mail. Unfortunately falling off a cliff isn’t the real danger here, that would be the Nazis. When Boy reads Jane’s letter about a world torn by war, and the threat of the Nazis, Boy remarks that Tarzan could easily kill those pesky Nazis like he killed Bolgat the gorilla, but Tarzan responds, “No, Tarzan killed Bolgat to save Jane and Boy. Why Tarzan kill Nazis?”
“What have Nazis ever done to us?”Tarzan’s attitude of isolationism was very much in keeping with how many Americans at the time felt, and the U.S. State Department informed Sol Lesser that Tarzan could be a great propaganda tool against fascism. Certainly fighting Germans was nothing new to Tarzan as he killed his fair share of them in such books as Tarzan the Untamed and Tarzan The Terrible.
Note: The Germans that Tarzan in the books by Edgar Rice Burroughs fought were the ones invading Africa during World War One or The War to End All Wars as it was called at the time. The movie really jumps the timeline forward a tad so that Tarzan can fight the current German threat.
Throughout Tarzan Triumphs Tarzan has to practically be dragged kicking and screaming into the fight. Which was pretty much the way America entered WWII. Only when Boy is threatened does the fierce Lord of the Jungle make a stand.