My understanding of de Gaulle's background is that he was largely an analyst-type of general without any nationally-known heroics from WW1, and that his highest pre-WW2 French governmental position was Undersecretary of State. My guess is that the Radio London broadcasts made by de Gaulle were the instrument that gave him credibility as the leader of the Free French. It is also my assumption that those broadcasts were made only after a carefully measured assessment by Churchill, et al, that de Gaulle was the leader they wanted to be installed of the wartime and also post-war France. Considering that de Gaulle later would have a reputation for frosty relations with allies, were there concerns at the outset with propping up de Gaulle, or was he the clear and obvious choice to support?
de Gaulle was really nobody in Britain or the US's first, second, or even third pick for the most part. He was just the one who came out on top, didn't get killed, and out maneuvered the rest in the jumbled mess of French forces and spheres of power that existed on the Allied side. He was deeply unpopular with many senior leaders such as Churchill and Ike, but by the end made himself the indispensable French leader. He was considered obstinate, stubborn at times, with a very high opinion of himself and perhaps an over inflated sense of where France now stood in the Allied force structure(traits he honestly shared with most other remaining senior French leaders and plenty of non French to be sure). But he also got results and was one of the first and few to never flirt with cooperation like Vichy.
In particular we can look at 2 other Frenchmen that the Allies sought to coopt as leaders of French forces first to ease the landings in North Africa, then to build a new French Army. The two are Admiral Darlan and General Giraud.
Darlan emerged as essentially the #2 man in Vichy, but also still commanded the military. As the naval chief his promises to not allow the Germans to seize the fleet were not believed by the British and their forcefulness and lack of trust in him eventually led to their attack on the French fleet at Mers-el-Kebir which soured just about all prospects of Vichy-UK cooperation. But that didn't mean Darlan was very pro Germany, and while certainly he could be considered as actively collaborating at points he also toyed with siding with the Allies. Key to this then was his position as the Chief of all Vichy forces, and by chance being in Africa when TORCH was launched and his willingness to deal and talk. His cutting a deal to order the stand down of French forces greatly eased what had been stiffer thane expected resistance to the landings. He also began to put together a French force based in Africa wholly separate and larger than de Gaulle's under Darlan's leadership. But a few weeks into his cooperation he was killed by an assassin who was a radical anti-Vichy French Monarchist. Darlan was not popular himself but his relative power and willingness to deal were convenient and smoothed over enough of the outcry for working with such a prominent Vichy leader. Churchill's confidant MacMillan famously said of him "Once he was bought, he stayed bought". But his death removed a major competing power bloc to de Gaulle's in the French Allied forces.
This then brings us to General Giraud, who had taken an active role in the start of the war but was captured in May 1940. He then escaped and was protected in Vichy from recapture and actively agitated against too close a relationship with the Germans. This also began a period of clandestine talks with the Allies for preparation to land in North Africa and the eventual liberation of France. He was taken by sub from Vichy to Gibraltar then to meet with Ike in November 1942 just before TORCH. However he had quite the inflated opinion of himself and at first refused to cooperate when he found out they only wanted him to command the French contingent of the eventual force in Africa, not all of it, and that the damn Brits were participating!
Eventually he caved but his not being an official part of the French command structure in North Africa meant his calls for joining the Allies and not resisting were generally unheeded. Hence why Darlan's being caught in Africa and willingness to cut a deal was so important. Giraud though did have his uses and became essentially the field commander and #2 at first under Darlan in Africa, and became the commander of all French forces in Africa after his death. And there began a sort of courtship and coming together of his forces and de Gaulle's, with them initially sharing power. But de Gaulle eventually forced him out, and Giraud's inability to be a team player eroded his use as an Allied commander and he ended the war retired without a command or post of any sort.
(If this answer isn't sufficient, feel free to erase and i can resubmit it on the weekend.)
i can answer this this weekend if you don't get an answer before then. Off the top of my head it was between de Gaulle and Giraud (and depending on how you want to view it, Darlan). The other two sort of fell by the wayside either a)by being captured or b)by being Vichy, then turning to the Allies and then getting assassinated.
de Gaulle according to Fenby in The General tried to modernize the French army in terms of tactics, using tanks as proper battalions instead of support role (you'll have to forgive me any military terminology that is incorrect as 1) i'm not knowledgeable about the military and 2) my books are at home.
de Gaulle wrote a lot of papers trying to get the Military brass to change their way of thinking. I think that's what he's best known for pre-WWII. He didn't really do much in WWI except for get some sort of injury that he ended up sitting out most of the battle, iirc.
He was the choice of Churchill as far as he was willing to play second fiddle to Churchill's wishes, which was never his way. There were lots of times that de Gaulle was in and out of favour with the Allies because of the way he did things, ran his missions, and/or refused to play along with the big 3. I do remember that Roosevelt had a big problem with de Gaulle and can't remember exactly why that was but i know that de Gaulle always had the impression that the Americans wanted a say in how france was governed after the war and thought that France was not on the side of the Allies. He probably did more to move him away from Churchill than any other person save himself.
Considering that de Gaulle basically invented the role of leader of the Free French himself based on those radio broadcasts is right but it was never a given that he would be the leader post-war. He had a difficult time convincing other non-French that he was the best option during and after the war. In a side note, Churchill's cabinet started proofing the speeches after a few problems arose but de Gaulle was always known for going off-script.
I would say he was never the clear and popular choice to support but he was the obvious one.
A really good book for this is Fenby's The General