On the 6th February 1934, when the far-right attempted to take over in France and depose the Cartel des Gauches government. IOTL, they didn't go the whole hog, and were slightly mollified when the left-winger Daladier was replaced with the former president, Gaston Doumergue, by President Albert Lebrun.
But – what if the far-right had held their nerve and attacked the Assemblee Nationale? The POD here is that they do so, and rather than actually take power, they have be mollified to a more intense degree. Lebrun appoints Marshal Petain as the new Prime Minister rather than merely as Minister for War, in the hope that this will do the trick.
The PoD is this: Instead of wavering and deciding against going on the offensive, as IOTL, the Croix-de-Feu waver and then go for it. Their leader, Colonel de la Rocque, was reluctant to riot, but not utterly unconvincable.
The police were struggling by now. Although they had nearly contained the rioters on the Place de la Concorde, the situation to the south of the Assemblee Nationale was getting worse. It was looking more and more like the Croix-de-Feu were engaging in disturbances outside the building, and some were striking out to harry the police.
At just after 11 o'clock, the breakthrough came. Croix-de-Feu demonstrators broke the police cordon around the other rioters, and a pitched battle began. The police were overwhelmed. In the chaos, members of Action Francaise forced their way into the Assemblee Nationale. This is notable for the beating handed out to the Minister for Education, Anatole de Monzie, who was present at the time.
The battle raged inside the building for over an hour, resulting in 4 deaths (three rioters, and the SFIO deputy Roger Salengro). Most of the deputies fled, and Daladier was forced to request a state of emergency from the President, Albert Lebrun.
At 3 o'clock on the morning of 7th February 1934, unable to persuade the police to follow his orders or to get his own cabinet behind him, Daladier tendered his resignation to Lebrun. Lebrun accepted it, but was unsure who to put in place. Who could mollify the far-right but be acceptable? Doumergue was popular but too soft. Chautemps was not acceptable. He needed someone who had a good reputation amongst the hardliners but who was popular in the country as a whole.
At 6 a.m., exhausted, Lebrun summoned the Hero of Verdun, Marshal Philippe Petain, to the Elysee.