Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.
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Question: a rearguard is a part of a military force that protects the main force from attack from the rear.

Answer: rearguard


Question: colonel archibald gracie iv (january 17, 1859 – december 4, 1912) was an american writer, amateur historian, real estate investor, and survivor of the sinking of the r.m.s titanic.

Answer: archibald gracie iv


Question: agenville is a commune in the somme department in hauts-de-france in northern france.

Answer:
agenville