Jerome Beers Thomas, Jr., who came from a prominent family in Brooklyn, New York, was the son of a physician who had served in the Civil War. The date of birth of Jerome Thomas, Jr., is unknown, but it is known that he followed his father into medicine. Where young Thomas attended medical school is also unknown, but his specialty was eye, ear, nose, and throat.

Mary Dension Wilt and Dr. Jerome Beers Thomas, Jr., had been married four years when he was sent in 1900 to the Philippine Islands as a contract surgeon for the U.S. Army. According to Denison, as she was called, Jerome had offered his services to the Navy when the war with Spain was declared in the spring of 1898, “but the boats made him too sick” and he transferred his services to the Army. Although the Spanish-American War ended in December 1898, The United States still maintained an Army presence after the war in the Islands with the dual mission of putting down insurrection, which had reasserted itself after the peace treaty was signed, and of seeing that the U.S. Commission established under the treaty could go about its work in relative safety while preparing the Philippines for democratic self-government after its 300 years as a Spanish colony.

Denison Wilt was born in Dayton, Ohio, and was graduated from Wellesley College in Massachusetts. By her own account, she was an avid student and a keen member of the women's rowing crew. She also developed a precise talent for sketching and watercolor painting. She cheerfully said goodbye to her husband when she learned of his new posting to the Philippines, knowing that she could soon join him, now that formal hostilities had ended.

Jerome left from New York for the Philippines, traveling east by Army transport to Gibralter, Port Said, Suez, Ceylon, and Singapore to Manila. Denison sailed from San Francisco a few weeks later, also by Army transport ship, sailing by way of Hawaii and Japan to Manila. Their first home in the Philippines was at Angeles, not far from Manila. From there, Jerome was sent to Apalit, where he became so popular among the villagers that the Filipinos name a street after him. While Jerome was occupied treating civilians and soldiers, the latter mainly for dengue fever and dysentery contracted in their campaigns to root out insurrection, Denison maintained her house, studied Spanish, grew to know the people, and explored the countryside, her camera and pencil always at the ready. She made friends wherever she went and was rarely without company. A frequent companion was Miss Mercy Brett, Jerome's cousin, who had come out to the Islands with Denison on leave from her job in Ohio at a Soldier's Home.

From Apalit, Jerome was sent to Taglibaran (Bohol Province), where he served not only in the field hospital but joined the troops occasionally on their sorties into the hills after guerillas. He was given a commission in the U. S. Army as a Captain, and in March 1902 was rushed to Manila to help combat an epidemic of cholora. Later that year, the Thomases were among those sent to Baguio (Benguet Province), when the mountain village was transformed, with Army help, into the Philippine summer capital, owing to its cooler altitidues, away from Manila's stifling summer heat. Here, Jerome oversaw the building of a large, modern hospital and was named to be its director at its completion. Baguio remained the Thomas's home until they returned to the United States in 1905.

Denison and Jerome Thomas enjoyed the friendship of a number of highly placed U.S. officials in the Philippines, including High Commissioner, and later Governor General, William Howard Taft, formerly a judge in Cincinnati, Ohion, and his successor, Luke C. Wright. Commissioners Henry Clay Ide, Bernard Moses, and in particular, Dean C. Worcester and his family, were also their friends. These connections brought the young couple into the white-linen-suit circles typical of the upper ends of society in several tropical countries of the period that were under foreign protectorates. As a consequence, the Thomas letters contain many references to dinner parties, balls, picnics, and horseback trips into the bush. But along with these diversions of their circle of friends, the Thomases were genuinely interested in U.S. and Philippine relations and in their surroundings and friends among the Filipinos and native peoples of the Islands. They spent many hours recording their experiences in writing, sketching, and photographing what they saw and heard.

Details of the Thomas's life on their return to the United States are few. It appears that Jerome resumed his practice in the New York, from late 1905 to 1910, when he became ill, and was advised by his physicians to seek a warmer climate. The couple chose California, living in Santa Cruz for a time, and then settling in Palo Alto in 1913. Jerome became a well-respected physician in his specialty, practicing until 1917. Dension took an active role in civic affairs, becoming one of two women to first be elected to the Palo Alto City Council in 1919-1923. During her tenure she was instrumental in the City's acquistion of some 930 acres of bayside marshland, and after her City Council days, she served on Palo Alto's Planning Commission. She was a member of the Sierra Club, and, although the couple had no children, she was very active in the Parent-Teacher Association. Both Denison and Jerome served on the Palo Alto Board of Public Safety. In World War I, they were active in Belgian War Relief, and on the Committee to Defend America by Aiding the Allies in World War II.

The couple lived at 1432 Webster Street in Palo Alto. Jerome died in 1948, and Denison, a charter member of the retirement community of Channing House, died on July 1, 1983, at the age of 108.