Three years after his succession, he embarked on the Great Northern War against the encircling powers of Denmark, Poland-Saxony, and Russia. In the early years he won a series of victories, but in 1709 he embarked on an expedition deep into Russia that ended in the destruction of his army at Poltava and the internment of Charles until 1715. He resumed his military career after his return but was killed while besieging a fortress in Norway.