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What is the main idea of the passage?, Context: After Kerry's third qualifying wound, he was entitled per Navy regulations to reassignment away from combat duties. Kerry's preferred choice for reassignment was as a military aide in Boston, New York or Washington, D.C. On April 11, 1969, he reported to the Brooklyn-based Atlantic Military Sea Transportation Service, where he would remain on active duty for the following year as a personal aide to an officer, Rear Admiral Walter Schlech. On January 1, 1970 Kerry was temporarily promoted to full Lieutenant. Kerry had agreed to an extension of his active duty obligation from December 1969 to August 1970 in order to perform Swift Boat duty. John Kerry was on active duty in the United States Navy from August 1966 until January 1970. He continued to serve in the Naval Reserve until February 1978.
Output:
John Kerry was on active duty in the United States Navy from August 1966 until January 1970. He continued to serve in the Naval Reserve until February 1978