Mary Teresa Giesenhaus

Mary Teresa O'Day Giesenhaus, 92, passed away surrounded by her family on December 23, 2025, at the home of her daughter Cathy in Frederick, Maryland.

Mary was born in New York City on November 10, 1933. She grew up in the city with her sister Noreen until the passing of their mother in 1939. Mary was then lovingly raised in Smithtown, Long Island, by her great-aunts Margaret, Kate, and Julia.

Mary graduated from High School in 1951 and moved to Brooklyn Heights at age 17. While working at Western Electric, she met the love of her life, William Frederick Giesenhaus. They married on November 16, 1957, beginning a devoted 41-year marriage that lasted until Bill's passing in 1999.

As their family grew to include four children, Mary and Bill made homes in Jersey City, NJ; Middletown, NJ; and Lutherville, MD, before settling in Vienna, Virginia, in 1970. Mary dedicated herself to managing the household, volunteering at school events and in the community. She worked part-time throughout the years and found joy in bowling, beach trips, swimming, and cruising.

In 1997, Mary moved to Rehoboth Beach, where she became an active member of the Old Landing Social Club. She loved planning events with her neighbors and cherished the friendships she made there. Whether heading to the casino, going out to eat, shopping, or thrifting, Mary embraced every outing with enthusiasm. She traveled often with her family – cruises, beach vacations, mountain trips, and weekend getaways – and treasured every moment spent together. She delighted in having visitors at the beach and thrived in the lively bustle of a full house. Mary was always ready for fun and never turned down an adventure.

Mary is survived by her four children, nine grandchildren, and one great-grandchild, all of whom will miss her dearly.

A Mass of Christian Burial will be celebrated on Tuesday, January 6, 2026 at 11:00 AM at St. Edmond Catholic Church 409 King Charles Avenue, Rehoboth Beach DE. Visitation will begin at 10:00AM. A Graveside Service will follow at 12:00PM at Epworth Methodist Cemetery. 187 Henlopen Avenue, Rehoboth Beach DE.

Please sign Mary's Tribute wall at this site.

FLORIST NOTE - DELIVER ALL FLOWERS BY 3:00 PM TO LEWES LOCATION ON MONDAY JAN 5, 2026.