With the release of "One Piece" Chapter 815, the Vinsmoke family plot has definitely thickened and in Chapter 816, fans could expect more revelations about Sanji's family, including the background of his father, which according to a report (via YouTube) is based on Adolf Hitler!
It was Alpha2late17 who presented a wild yet really interesting theory about who may have inspired the character of Sanji's father.
According to him, Germa 66, the mythical army headed by Sanji's father, and which had caused several wars in many countries, is inspired by a German Nazi submarine called U-66. And Sanji's father being the leader of Germa 66, is inspired by the Nazi leader, Adolf Hitler.
The theory by Alpha2late17 highlighted how "Germa" in the name Germa 66 sounds short for Germany, known to where Hitler's movement started. The report speculated that the organization of assassins is travelling through submarines because quite incidentally, there was also a German Nazi submarine named U-66.
The use of submarines fits for Germa 66 as it might explain how the group could pass through the red line from the North to the East Blue. This may also explain how Sanji was able to get to the East Blue.
Furthermore, it was hugely rumored that Adolf Hitler had a French son named Jean Marie-Loret. While it was not proven if this was true, Loret claimed that her mother, before she died, admitted to him that he was the son of a soldier during the World War I, the soldier in question being Adolf Hitler.
Jean Marie-Loret, therefore, represents Sanji, who may have been born during a war between the Germa 66 and the World Government, much like the World War I and II. And just like how it was speculated that U.S. government only claimed to have won the war when the truth was the Nazis only escaped, Alpha2late17 thinks the same happened with the World Government and Germa 66. The reason why Germa 66 is called a "mythical army" (also recognized by Nami) is that the World Government covers up their existence.
After the World War II, the U.S. government recruited over 1,500 Nazis and in the same way, the World Government may have recruited Germa 66, which explains why Sanji's bounty was revised.