instruction:
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.
question:
Context: the group originally included lead vocalist Keith Relf Link Information: The Yardbirds are an English blues rock band from London. Formed in May 1963, the group originally included lead vocalist Keith Relf Answer: Robert Plant
answer:
Which person was the lead singer of the Yardbirds the longest?


question:
Context: he announced he had decided to support and vote for Mitt Romney for President, even while continuing to serve as a D.C. elector for Johnson. Link Information: Johnson was born on January 1, 1953, in Minot, North Dakota, Answer: North Dakota
answer:
What state is the candidate Barron served as an elector from?


question:
Context: The same year he served on the staff of General Eduard von Bonin in the First Schleswig War, Link Information: Bonin was promoted to Generalleutnant and named Minister of War in March 1852. Answer: 1852
answer:

When did the person who von Blumenthal served under  in the First Schleswig War first achieve their rank?