The French do eat horse meat (viande chevaline), but hardly as much as they used to. They will be happy to tell you it is leaner than beef, full of iron, tastes similar to beef and was the original meat used in steak tartare.
In the countryside where people couldn’t afford to let anything go to waste, they ate horses, as they did across the world in spite of a papal ban of 732 (banned, not because the pope had any special fondness for horses, but because Germanic worshippers of Odin ate them and they were associated with paganism).
Attitudes officially changed with the Revolution, when people were starving; not only did they lop off the heads of the aristocrats, but they also ate the duke’s and count’s horses. In the Napoleonic wars, soldiers were reduced to eating their steeds, notably at the Battle of Eylau of 1807. Napoleon himself flavoured his cheval steak with gun powder.
Images by Fæ on Wikimedia Commons, LPLT