Between 1742 and 1747 illegal trade between landowners in Costa Rica and with British Jamaica and the Baymen of the Mosquito Coast (of present-day Nicaragua) were stopped as a result of the fort.

[7] In April 1747 a group of British baymen and Miskitos took about ten prisoners near Matina and threatened to burn the plantations and invade Cartago if trade was not resumed with them.

The commander of the fort was Don Francisco Rodriguez, and together with the reinforcements ordered to put permanent lookouts in places where they could watch any approaching British troops to avoid surprise.

[5] Transported by Pirogues from Jamaica they landed in Moin near Limón, which beyond had an extensive swamp – the Spanish thinking it was impassable had no lookouts in the area.

The high Canebrake meant they were concealed and watched patiently for five days studying the defences and awaited for the right moment to attack.

Quickly the British soon found weaknesses in the perimeter where they could fire their muskets at close range – this caused confusion inside the fort.