The island's population was mostly favourable to the Vendéens, and its situation off the Atlantic coast was of strategic importance to communicate with Great Britain, or even to receive English or émigrés reinforcements.

During the night of 28 September, Charette had already tried attacking the island with 2,000 men, but his soldiers fled after the first shots fired.

On 9 October, Charette and his 3,000 men left Legé, which the republicans of general Nicolas Haxo occupied the next day.

Charette first marched towards Saint-Gilles-Croix-de-Vie, but seeing the town was well defended he finally went to Bouin on 11 October and had his troops stationed there.

With no other choice, the Vendéens launched an attack and captured by surprise the artillery north of Barbâtre which was guarding the passage de Goix.

They then marched to the north and pushed back a republican detachment at the pointe de La Casie.