Pierce started on his evangelistic journey travelling to China with Youth For Christ. His daughter Marilee Pierce Dunker later wrote "My father went to China a young man in search of adventure, and he came home a man with a mission." He dragged his camera across Asia making films, which he showed to people, begging them to help just one child. Can you help one child? He desperately wanted to shake people out of their complacency and turn their hearts to God and helping children in need.
He was a man of strong emotion, leading with his heart, which was both a good and a not so good thing. It helped him talk with large groups of people and they could see his heart for the children he was so desperate to help which in turn help them to see and feel the need to help these children but the flip side was his anger and he would have angry clashes with the Board of World Vision.
The ministry was conceived in 1947, founded in 1950, formal sponsorship beginning in 1953, Pierce left the organization in 1957.
He worked tirelessly for World Vision except when his health and mental stasis determined otherwise. Clashes with the board led to his being fired. From his efforts an organization that now cares for more than 1/2 a million children worldwide was made.
He also helped in the formation of Samaritan's Purse. It was a small hunger organization when he took over running it in 1970. He continued to be lead by his statement "Let my heart be broken with the things that break the heart of God." He lead this organization until Franklin Graham took it over. He died in 1978 from leukemia.