Dennis was born April 4, 1929, to parents William Penn and Pauline Dennis.

He grew up on the Shinnecock Indian Reservation and attended the Shinnecock One Room School House.

Later, while in his 50’s, he completed his high school education, received a diploma and went on to study and pursue a career as a Substance Abuse Counselor.

He introduced a sobriety recovery program in the Shinnecock Nation over 60 years ago that still thrives today.

Dennis’ love of planes prompted him to enlist and serve his country honorably in the United States Air Corps during World War II where he gained rank as Sergeant.

After being honorably discharged, he returned home to the Shinnecock Nation and worked at the U.S. Post Office for 20 years until he retired.

In 1949, he married Dorothy Smith and together they had 8 children.

For 19 years, Dennis served as a Shinnecock Tribal Trustee and will be remembered as an exceptional Tribal Leader.

During his term he advocated for land rights, federal recognition and protecting the Nation’s sovereignty.

Dennis was also an Elder of the Shinnecock Presbyterian Church and an active member of the Shinnecock Community.

He enjoyed attending and participating in civic, Native American events and powwows.

He spent his time boating or working on his boat “Chief Eagle Eye”, fishing, swimming and traveling the states with his wife.

To his close friends he was also known as “Hammer!” and could be described as a stern but kind-hearted man.