Lauder hired a band of one hundred pipers to travel with him through Scotland in order to recruit soldiers for World War I. His only child, a son named John, was killed in Poiziers in France in December 1916. Harry and his wife, Ann (known as Nance) were heartbroken and in an effort to deal with his grief, Lauder tried to sign up but was refused on the grounds of his age. Instead, Lauder was named as the first battlefield entertainer. He travelled all over the theatre of war entertaining the British and American troops in dangerous and difficult conditions. When he saw the injured and disabled soldiers in the war hospitals, Lauder pledged to donate some of his concert profits to a fund that would supplement their meagre government payments when they returned to civilian life. He was also a Rotarian with an international reputation and assisted many good causes in both Britain and America. He was knighted in 1919 shortly after his wife had died.