[1][2] Morse began his career as a freelance writer for national magazines, such as Harper's Bazaar and he won recognition in this field, including the Sigma Delta Chi's annual award for "distinguished public service journalism".
[2][3] Morse was the author of several books on the social issues of his time, such as Schools of Tomorrow — Today published by Doubleday in 1960 and covering diverse topics such as team teaching and summer programs for gifted students.
[7] Morse's best selling book, While Six Million Died: A Chronicle of American Apathy, published in 1968 by Random House, concerns the controversy over the United States and Allied response to the Holocaust during the Second World War.
Morse indicts the Roosevelt administration, and particularly the US State Department and certain officials in it responsible for refugee and Jewish affairs, for failing to act when there was a possibility of rescuing substantial numbers of Jews from annihilation by the Nazis during the Holocaust.
He also criticized the British for supporting the rescue of European Jews while keeping Mandatory Palestine closed to refugees, and Pope Pius XII for his public silence in the face of the information about the genocide taking place that was made known to him too.