Q: In this task, you're given a context, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both context and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the context or linked information.
Context: The first book starts in 42 AD. Link Information: The first book starts in 42 AD. The books cover the experiences of the two soldiers, initially as experienced centurion and new optio, in battles in Germania and the invasion of Britain by Claudius as part of the Legio II Augusta. Answer: 12
A:
How old was Claudius at the start of the first book?