Meanwhile, a lasting peace with France was made in 1558 and the initial invasion threat passed. The Spanish threat to the south-west of England became more serious, however, and war broke out in 1569. As a result, a defensive earthwork was constructed north-west of the castle to protect it against an attack from the land, and an additional gun battery facing upriver was installed alongside the blockhouse. The levels of the garrison varied considerably during the period. Pendennis had a garrison of 100 men in 1578, and could have mustered around 500 men in 1596, while in 1599 it was reportedly guarded by 200 soldiers.