On War Against the Turk (German: Vom Kriege wider die Türken) was a book written by Martin Luther in 1528 and published in 1529. It was one of several pamphlets and sermons by Martin Luther about Islam and resistance to the Ottoman Empire, during the critical period of territorial expansion of the Ottoman Empire in Europe, marked by the capture of Buda in 1526 and the Siege of Vienna in 1529.