Daniel Buckley, Jr. was the son of Daniel Buckley, Sr. and Abigail Sullivan of Boherbue, County Cork, Ireland. In 1905, they moved to Ballydesmond (then Kingwilliamstown), where his father served as the town's baker. Like many other Irish young people at the time, Daniel felt that he could have a better life and make more money in the United States. By 1912, he and a group of friends decided to make the long transatlantic voyage on the Titanic.
Since Buckley slept in a third-class cabin near the ship's bow, he could hear the sound of the crash when the ship hit an iceberg. He immediately thought that something was wrong, but his bunkmates didn't believe it was serious, though when he turned on the light, they could see water on the floor. Buckley went up to the boat deck and was among a group of steerage passengers who forced their way through a locked gate. More trouble arose when the men in the lifeboat Daniel had gotten into were ordered out, supposedly at gunpoint. However, Buckley attempted to hide at the bottom of the boat and a female passenger threw a shawl over him, thus disguising him as a woman. He believed that his savior was Madeleine Astor, though according to historical record, it seems more likely that she was a Mrs. Appleton, as Mrs. Astor was in a different lifeboat.
After his safe arrival in America, Daniel settled in Manhattan, where he worked in a hotel. In June 1917, he joined the army for World War I. He was in the 69th Regiment, which was made up entirely of other Irishmen. After undergoing basic training at Camp Mills in Long Island, Buckley arrived in France in the fall of 1917 with Company K of the 165th U.S. Infantry (which the 69th Regiment had been reconstituted as). In October 1918, Buckley was killed by a sniper while helping to retrieve wounded soldiers on the Meuse-Argonne front. He was initially buried in France, but his remains were taken to Ireland in the spring of 1919.