Sooo, nobody replied yet so let's start. I own several books about Charles de Gaulle, Philippe Pétain, and even a book all about their relationship. I LOVE them, they're my first and second favorite historical characters of all time. I also own stamps, records, you name it, I'm a big fan. I'm french, so expect lots of french names and of course lots of mistakes ! Also, keep in mind I do not approve of everything they did, Philippe's collaboration and Charles's involvment with african governments weren't things to be proud of.
Pétain was Charles's teacher at the Ecole de guerre (a french military school for officers). My coworker (a french captain) saw Charles's tests, corrected by Philippe Pétain, at St Cyr l'école.
Charles ghostwrote a book for Philippe, because he needed to write at least one book to be a member of the Académie française, that book is called "La bataille de Verdun". Charles was a very educated man, pretty experienced in writing (about military stuff of course, but he also wrote erotic short stories), while Philippe came from the countryside : both of his parents were agricultors. He was a country man and a soldier, but not a very good writer.
They both fought at Verdun (I live very near), but Charles spent a lot of time in Germany as a prisoner of war. Pétain was then a general. He was the man behind the "voie sacrée", a road that connected the countryside and the battlefield. Night and day, trucks were driving on that road to supply the many french soldiers fighting in Verdun. His goal was to spare as much men as possible and to keep their spirits up. In 1918, after the armistice, he was made Maréchal de France, in the city of Metz, where Charles lived for a few years with his children and his wife, Yvonne. If you need any pictures of Charles's house or anything, just ask !
In 1940, Charles and Philippe took different paths : Philippe was asked to lead France by the Parliament, then signed the armistice between France and Germany. He only had power on the lower half of the country, the upper half being occupied by the german army. The germans also annexed Alsace and Moselle, where Metz is located, for the second time (first time was in 1870 after Napoleon III's defeat at Sedan, and Maréchal François Bazaine's in Metz). Vichy France collaborated with Nazi Germany. That's facts. Pétain was an important part of Vichy propaganda, he even had his own song "Maréchal nous voilà", sung by popular french opérette singer André Dassary. As he was a national hero, most people admired him and had no problem following his orders. Pétain's personal flag featured a francisque made of his baton and the french flag.
Charles became the leader of the "France libre" aka the french resistance. His symbol is the "Croix de Lorraine" (a french region, where Metz and Verdun are located, also my homeland). Along with Leclerc and De Lattre de Tassigny (and all of our other allies, Lorraine was liberated by american troops, let by Patton among others, and a lot of historical reconstitution groups are very fond of GIs), he liberated France from the enemy.
During the war, Vichy's government sentenced Charles to death, but Philippe made sure he wouldn't be executed.
After the Liberation of France, many collaborators, including Pétain, were judged and sentanced to death, prison for life or forced labor. Philippe Pétain, was sentenced to death, but he was instead locked in a fort on some remote island called île d'Yeu. He's now buried there. He died in 1951, aged 95.
A bit later, in 1958, Charles became president. He once publicily said that Philippe Pétain was a good leader in Verdun, an opinion that's shared by many french presidents, from Mitterrand, former collaborator, to Emmanuel Macron, our current president.