As we all know Charles de Gaulle was the commander of the Free France that liberated France from the Vichy regime and from the German occupation. After that victory, though, he was the chairmen of the Provisional Government for only 1 year, 268 days before he disappeared from the political scene. So why wasn't the liberator of France and the hero of the nation during WW2 the President of the 4th Republic?
It's unclear what exactly this q is asking. But de Gaulle quit in '46 and his plans for a constitution closer to his vision didn't get much traction back then (unlike later in '58):
About a week after the second assembly began working on a new draft, de Gaulle finally spoke out on his desired constitution in a speech at Bayeux on 16 June 1946. His proposal actually fell short of a true presidential system[...]. Its basic features were a separation and balance of powers, a president elected by an electoral college including the members of parliament, a government named by the president, and several mechanisms to give the government greater stability and independence from the legislature. Meanwhile, the Constituent Assembly continued its work, basically ignoring de Gaulle's plan.
So yeah, one could say he retired just so he could "write his memoirs", but this came in a context of his constitutional vision being rejected by the political forces of the day in '46.
Interestingly, a single public opinion poll was conducted in this period (roughly) on de Gaulle's constitutional ideas/vision, namely in Oct '45:
In response, 46 percent favored the presidential system, 39 percent opposed it, and 15 percent offered no opinion.
This was in fairly stark contrast with de Gaulle's personal popularity back then (which was measured by more than one poll), e.g.
one from August 1945, in which 71 percent wanted de Gaulle as provisional president
Some historians thus argue that if only de Gaulle had pushed harder for his constitutional vision in public speeches etc., he might have prevailed even then.
Throughout 1945, de Gaulle made only vague statements about his constitutional program, while the parties campaigned energetically, calling de Gaulle a dictator and urging approval of their own political blueprints. [...]
Many of the general's supporters urged him to form a party in 1945, only to be turned away. They understood what de Gaulle did not understand: namely, that because the new constitution would be written by an elected assembly, only those inside that assembly would be able to determine its content. [...]
With no plans to field candidates for a third Constituent Assembly, de Gaulle lacked any legal mechanism for putting his constitutional ideas into place.
In this context, it's probably less surprising that de Gaulle chose to fund his own party (the RPF) in April '47, as he (finally) understood/accepted [that] the lack of a party base made him vulnerable to outmaneuvering in representative contexts like the Assembly.
His decision to (instead) quit in '46 did damage his standing with public though, at least for the next year:
Polls taken just after he resigned in January 1946 showed people split roughly evenly on whether they were pleased to see him leave the government, although by 47 to 28 percent, people felt he was justified in doing so.
Soon, however, his popularity began to decline, suggesting that directly or indirectly, quitting damaged his reputation. A poll taken just before his resignation found 32 percent wanted him to head the next government. [...] Two months later, only 16 percent wanted him to lead the government, though he still topped the list. During the general's retirement, pollsters continued to ask if people wanted him to return to power, with negative responses prevailing by about a 5 to 3 margin.
In the November 1947 elections, the first in which de Gaulle's newly formed Rassemblement du peuple francais (RPF) competed, the party finished first, with 38 percent of the popular vote.
However, that result would not have been enough to upturn the constitution of the 4th Republic to de Gaulle's vision.
Presumably de Gaulle was unwilling to be a president in a constitutional system (4th Rep.) he seems to have substantially disapproved of, although I'm not sure if there are any crystal clear statements of his in this regard. (His "Joan of Arc" analogies being a bit vague in this respect.)
Edit: So, I originally misunderstood your question. You're asking about before the Fifth Republic what he was doing.
Wikipedia says this about that time:
After monopolizing French politics for six years, Charles de Gaulle suddenly dropped out of sight, and returned to his home to write his war memoirs. De Gaulle had told Pierre Bertaux in 1944 that he planned to retire because "France may still one day need an image that is pure ... If Joan of Arc had married, she would no longer have been Joan of Arc".
So it seems he was planning to not come back in French politics for a while, having had some disagreements with how the Fourth Republic should be run.
That doesn't mean that he was totally inactive during that time:
In April 1947, de Gaulle made a renewed attempt to transform the political scene by creating a Rassemblement du Peuple Français (Rally of the French People, or RPF), which he hoped would be able to move above the familiar party squabbles of the parliamentary system. Despite the new party's taking 40 percent of the vote in local elections and 121 seats in 1951, lacking its own press and access to television, its support ebbed away. In May 1953, he withdrew again from active politics, though the RPF lingered until September 1955.
Finally, the Fourth Republic started to collapse, and de Gaulle came back into power, instituting the republic he had intended nearly 10 years ago.
I'll leave my original post here, in case anyone finds it interesting and informative.
That's because he founded the Fifth Republic of France not very long into his term as President of the Council of Ministers. He was the first president of the Fifth Republic. He would be so for another 10 years (1959-1969).
De Gaulle died a year or so after leaving office (in 1970), which is probably why you never heard a lot about him in French politics after that.