When ibn taymiyyah was young (about the age of 7) - the mongols attacked his town.. so when he became older - he had to fight against them. They were the oppressors and power of the world at that time.
erm.. i cant really say anything without facts, so you might want to check his biography out insha'Allaahu ta'aala.
Biography of Shaykh ul-Islaam ibn Taymiyyah
Shaykh ul-Islâm ibn Taymiyyah
He was the man who said something similar to: What can my enemies do to me? My paradise is in my heart - it goes wherever I go. To imprison me is my seclusion to worship Allaah, to take me out of my land is part of my journey to Allaah (to see His creation), and to kill me is martyrdom (shahadah) - what can my enemies do to me?
And throughout his life, he did get taken out of his homeland, and he was imprisoned many times. subhan Allaah..