The History of the Expedition of the Emperor Frederick (Latin: Historia de expeditione Friderici imperatoris) is an anonymous Latin account of the campaign waged by Frederick I, Holy Roman Emperor, as part of the Third Crusade. It covers the period 1187–1196, but is centred on the expedition of 1189–1190.
It appears to be a composite work, compiled from pieces written while the expedition was underway with a preface and an appendix added. Very early manuscript copies survive, but it is only a later 13th-century notice that first gives an author's name, Ansbert. This may be the name of the author or perhaps the compiler, but it is uncertain. The work is associated with Bavaria and Austria.
It provides a nearly day-to-day account of the expedition as it crossed the Balkans and Anatolia before the sudden death of Frederick I in a swimming accident. It is the most detailed surviving account of the expedition and it relies mainly on eyewitness reports.