Daniel J. Lennon was born in February 1925 in Vienna, Austria. His father was in graduate school for medicine. They returned to the United States a year later and lived in San Francisco for a short time and then moved Sausalito where Lennon grew up. Lennon commuted to San Francisco to go to Saint Ignatius High School. He remembered when the Golden Gate Bridge was built. He thought of it as an obstruction, and preferred ferry rides. As a kid growing up in Sausalito, he did a lot of fishing and sailing. After the attack on Pearl Harbor, he and some of his buddies volunteered to be aircraft observers on a ridge overlooking the Golden Gate Bridge. They would sit out there four hours at a time and report any aircraft activities. Lennon was drafted to the Army soon after his 18th birthday. He reported for duty in May 1943 in Monterey, California then was shipped to Fort Leonard Wood, Missouri for basic combat engineering training. Next, he was sent to Milwaukee, Wisconsin for additional training, and then to Camp Swift, Texas where he joined the 147th Combat Engineers [Annotator's Note: 147th Engineer Combat Battalion]. His unit was then sent to Fort Pierce, Florida for demolition training. Lennon specialized in small boat operations. His unit was eventually sent to Camp Kilmer, New Jersey before shipping out of New York on the Mauretania [Annotator's Note: RMS Mauretania].

Daniel J. Lennon remembered the voyage across the Atlantic Ocean was not particularly good for enlisted men. His unit [Annotator's Note: 147th Engineer Combat Battalion] was on D deck, which was close to the bottom of the ship. They had to sleep on tables and hammocks. The food was always some kind of stew. There must have been a high-profile person on the ship because they made it across in three or four days. Lennon's father was already overseas serving as the executive officer of the 30th General [Annotator's Note: 30th General Hospital]. He was able to visit him in London a few times. His father developed cancer and died in 1944. From January to mid-May 1944, Lennon and his unit were in Paignton, England, a resort town, near Torquay. They were there until beginning their D-Day [Annotator's Note: Allied invasion of Normandy on 6 June 1944] preparations. They then went to New Forest, England. To prepare, they went over their mission as a unit daily, studied the beaches and were shut in from the outside. They received great food and accommodations during this time. Just before the initial day, Lennon was staying in some barracks on an airfield due to a delay, and a German bomber flew over and hit the barracks beside his. There was only one casualty.

When Daniel J. Lennon and his unit [Annotator's Note: 147th Engineer Combat Battalion] landed on the beaches of Normandy, they missed their target landing point and had to work their way back. As soon as they reached a road that was parallel to the beaches, they were hit by an artillery barrage that felt like it lasted forever. Lennon recalled stepping on the face of dead man and apologizing to him. He and his unit managed to crawl up to the road and attack with small arms. They hid under and behind a truck for protection and then eventually made their way across the road. The truck was then blown to pieces. They moved up to their target area, fighting the enemy the whole time and connected with the rest of their unit. They began to dig trenches, moving bodies that were in their way. The next morning, they experienced scattered artillery fire, so he and a few other troops went to find the sniper. They found an abandoned German trench which they occupied for a few days. While up there, the 2nd Infantry Division was making their way up a bluff, when one of the 147th Engineers guys in the occupied trench accidently set off a German machine gun. Lennon saw the 2nd Infantry men scatter for protection. Luckily, no one was hurt, and they did not return fire. Lennon recalled traveling on a LCVP [Annotator's notes: landing craft, vehicle, personnel, or LCVP, also referred to as the Higgins boat] to reach the Normandy beaches. He could not see much except for the coastline and the bluff. There was too much smoke and the weather was bad. He saw a lot of burning watercrafts and dead bodies as he made his way onto the beach, but everything was blurry due to the smoke and weather. Survival was going through his mind, along with doing his job. As the Americans settled into Normandy, Lennon did a lot of general engineering rolls. He launched a boat, picked up manifests and supplies, and ferried people around. His unit eventually moved to a small town and took over some German barracks and then went to Jullouville, France to keep an eye on German raids coming from the Channel [Annotator's Note: English Channel].

When the Battle of the Bulge [Annotator's Note: Battle of the Bulge or Ardennes Counter Offensive, 16 December 1944 to 25 January 1945] was on its way, Daniel J. Lennon and his unit [Annotator's Note: 147th Engineer Combat Battalion] was shipped up to the fighting area. He was put on guard duty. The military was running short on cold weather gear and he was freezing. He heated water in his helmet and when he stuck his feet in the water, they swelled and turned black. The pain was incredible. Lennon was evacuated to Paris and was laid up in a hospital for two months. On Christmas Eve 1944, he was transferred to a hospital in England for another month and a half. When he was healed, he was reassigned to the 833rd Bomber Squad [Annotator's Notes: 833rd Bombardment Squadron, 486th Bombardment Group, 8th Air Force]. His main duty was to load bombs on B-17s [Annotator's Note: Boeing B-17 Flying Fortress heavy bomber]. He did this from March to May 1945. After the war in Europe ended, he continued to do general duties until he could go home. He was able to get some leave, and was in the Newark, New Jersey airport when the Emperor of Japan signed the surrender on the USS Missouri (BB-63). He kept receiving telegrams from the Army to stay home. Lennon was discharged in October 1945.

Daniel J. Lennon's father had cancer so he received special permission to see him before he died. In November 1944, while he was in Jullouville, France, he received a telegram that his father had passed. Lennon remembered when he was in the hospital laid up in the hospital bed, he had to keep his feet uncovered. While healing, he played cards, read books and chatted amongst the other patients. Lennon recalled a time when he was on leave in London, Germany shot a V2 rocket [Annotator's Note: German V2 pulse-jet rocket bomb] blowing up a building near him. Lennon thought that his job with the 833rd Bomber Squad [Annotator’s Notes: 833rd Bombardment Squadron, 486th Bombardment Group, 8th Air Force] was easy and it got him into shape. He would load 250 pound bombs into B-17 [Annotator's Note: Boeing B-17 Flying Fortress heavy bomber] bombers. While he was on leave in May 1945, the war in Europe ended and the military requested everyone to return to base. He was able to get a ride on a B-17 with some of the flight crew. They circled around Paris and Germany looking at all the damage.

Daniel J. Lennon was discharged from the Army in October 1945 in California. He used the G.I. Bill to go to college. Lennon signed up for the Army Reserves and when the Korean War began, his unit was called up. He served in the Korean War until he broke his wrist. Lennon remarked that he really did not talk about his war experiences until recently. He believed that fighting in World War 2 gave him more responsibility and a different perspective on life. He thinks that The National WWII Museum gives the public awareness of what people had to go through, and generations exist because of their sacrifices.