You will be given a context, a subject and a relation. Your task is to generate a question based on the subject and relation. The generated question should include the given subject. Try to use a minimum number of words that are not present in either context, subject or relation while generating question.

Context : He was the second oldest out of four children born to Richard John Kerry, a Foreign Service officer and lawyer, and Rosemary Isabel Forbes, a nurse and social activist.
Subject : John Kerry
Relation : military branch
Which entity was John Kerry a part of?