I've also heard some info on how during 1917 when France was out of money and literally on the verge of defeat (this was prior to US entry), the French general staff had plans to overthrow the government, blame the socialists for surrender and continue the war in the event of a French surrender.
Can anyone confirm/deny any of this?
First I've heard of it, though it's not impossible some officers might have been tempted.
However, the only story I know for certain has the coup the other way round. According to Richard M Watt [1] when Caillaux was arrested in 1917, his papers included a plan called "Rubicon" by which the pro-left General Sarrail was to be appointed CinC, Paris occupied by picked troops from Caillaux' home district, the Chamber dissolved or "sent on an extended holiday", and Almareyda and others like him appointed to key government posts. This plan, of course, was made in anticipation of Caillaux's own appointment as Premier, which was frustrated when Poincare chose Clemenceau instead
.
My own guess, though, given the state of morale at the time, is that either kind of coup would have led to the Army's rapid disintegration, and a near certain German victory.
[1] Dare Call It Treason Ch17, pp235-6