1795 Massacre - anybody know anything about this?

[Will]

I have posted this in North Western France, as it appears to concern the commune of Heussé (Manche, 50, Normandy) but as it is right on the border with Fougerolles-du-Plessis (Mayenne, 53, Pays de Loire), I am posting here too.

Not far from our house is a piece of granite by the side of a road, on which is a panel which reads:

"Ici fut massacreée
le 21 Juin 1795
la Famille de
Jean Baptiste le Dauphin
"Le Vengeur"
Chef Chouain
1774-1799

                        ASCM"

Does anybody know anything about this person, his family, or the massacre? My own searches have drawn a blank so far.