Q: Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
Context: The Battle of Mortemer was a defeat for Henry I of France when he led an army against his vassal, William the Bastard, Duke of Normandy in 1054.
Question: What is the date when Battle of Mortemer happened?
A:
1054