Born in Greenwood, Delaware, to Simeon and Anna (Curry) Pennewill, he attended public and private schools in Greenwood, and prepared for college at Reynolds Academy, in Wilmington, Delaware.
He graduated from Princeton University in 1875,[1][2] and moved to Dover, Delaware, to study law in the office of Nathaniel B.
[2] Pennewill gained admission to the bar in 1878,[1] and built a large practice in Dover,[2] including among his clients the Pennsylvania Railroad Company.
[1][2] On June 14, 1897, Governor Ebe W. Tunnell appointed Pennewill to a seat as an associate justice of the Delaware Supreme Court and Resident Judge of Kent County.
[2] He died at his home in Wilmington, Delaware, following a heart attack while having breakfast, at the age of 81.