[1] The castle was probably built by the Kirkpatrick family in the early to mid-13th century, possibly to replace the nearby motte-and-bailey castle at Garpol Water and command the valley of the River Annan to the east and the ravine formed by Garpol Burn to the south.

[1][2] In its earliest form, the castle comprised a four-sided enclosure with the entrance on the north wall.

The walls were protected by a broad ditch, except in the north where a causeway passed over a linked pair of fish ponds.

In the late 15th or early- to mid-16th century, the castle was adapted for use as an artillery fortification with the walls lowered and reinforced with masonry and earth.

[2] An inventory made of goods belonging to the deceased James Douglas of "Auchencassill" in October 1483 includes a folding table, a horse, a chalice and altar ornaments, a sword, a featherbed, bed curtains and canopy, and the hangings or apparelling of the hall, a cushion, a silver salt and spoon, kitchen ware, an eel crook, and other items.