Christie's is to offer two letters from John F Kennedy to the widow of a sailor who served with him aboard the PT-109 torpedo boat he captained in the second world war.
The lot is valued at $20,000-30,000 ahead of the December 4 sale in New York.
Kennedy describes Andrew Jackson Kirksey as "the most promising man on the boat�Ǫthe thought of you and your son was always with him."
He explains the circumstances around his death: "You may already have heard what happened to us that night off New Georgia.
"We were sheared by a fast-moving Japanese destroyer as we turned into them for a torpedo shot. Some of us were left on the boat, others thrown into the water. It took several hours for all of us to get together, and when we finally had, two men were missing. One of them was Jack.
"We could find no trace and no one reported seeing him. I'm truly sorry that I cannot offer you hope that he survived that night.
"You do have the consolation of knowing that your husband died in the service of his country. He left a fine reputation with all, and those of us who knew him think of him with respect and affection."
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