Seymour was born in 1915 in Newark, NJ to a Jewish family. He attended high school and went to medical school at the University of Michigan. Seymour was inducted into Army Medical Corps as 1st Lieutenant.
Seymour’s unit was known as the “tip of the spear” and was in the forefront of every major battle in Europe from the invasion of Normandy to the end of the war. Seymour married his American fiancée in France during the war. His unit was ordered in April, 1945 to proceed to the Black Forest area to head off what seemed to be a large group of German forces, but when they arrived, the enemy troops were gone. However, they learned that a large concentration camp was nearby. This camp was a satellite camp of Dachau. Seymour never learned the name of the camp. His unit was ordered not to enter the camp, but to lock it up until a special army unit arrived to liberate the prisoners and give them medical attention.
Liberating the camp left Seymour angry at the Germans. To his frustration, townspeople who worked at the camps and saw the atrocities that were taking place, denied any knowledge about what had happened.
When Seymour went back to the United States, he opened up a medical practice in New Jersey which was very successful. He lived there with his wife and four children. Seymour wrote and published work relating to his experiences.