Clark got his Private Pilot's Licence when at Harvard University and was inducted into the Army 18th October 1942, earned his wings and was commissioned at Blytheville Arkansas in February 1944. He was not assigned an air crew until that November - having been employed as a ferry pilot in the interval - and they embarked for England in March 1945. His first mission was to bomb the Templehof airfield at Berlin, his worst on April 10 when all four engines went dead and the plane's interior was set on fire. All parachutes were destroyed so they couldn't bail out. They glided down to 3,000 ft - having thrown out everything that wasn't nailed down - just preparing to ditch when two engines fired up and they were able to make it back to base.

In civilian life he continued to fly in his own private plane, earned a Master's Degree in Business Studies and worked as an investment banker in New York before becoming Vice-President and head of the Trust Dept. in 1st National Bank Palm Beach FL.