Denis O’Sullivan was born on November 22, 1835 in Killarney, Ireland. In his early life Dennis signed his name as O’Sullivan, as can be recognized in many of his military records, his marriage certificate and later letters and papers. Through carelessness over the years Dennis eventually dropped the “O” from his name and his discharge from the U.S. Army gives his name as “Dennis Sullivan”.

Dennis married Mary Sullivan on June 19, 1859 in the Catholic Church at Killarney, Ireland. Mary was also born in 1835, making her about the same age as Dennis. Mary Sullivan was the daughter of Mary McCarthy and Humphrey Sullivan, who served in the 75th Regiment of the British Army; during which time he served in Sydney, Australia between the years 1801 and 1812. During that same period of time, Sir Henry Brown Hays was in Sydney as a convict. Sir Henry Brown Hays built the first hospital at Newcastle and was considered an eccentric Knight and convict adventurer. In 1801 Sir Henry had been transported to New South Wales for kidnapping an Irish heiress, Mary Pike, and seven years later he was sent from Sydney to toil in the Newcastle coal mines. It was during his Newcastle stay that Sir Henry built Bachelor's Hall which became the first hospital after Hayes left Newcastle around 1810. He was born in 1762 and died in 1832. Humphrey Sullivan was discharged from the British Army due to a broken leg from a fallen tree and received a pension of 1 pound, 2 pence a day; due to having his good conduct stripes. In addition, he received a grant of 15 acres in the Sydney area, but returned to Ireland upon his discharge and took no further interest in the land. Family oral history relates the land, which they lost out on, was in the vicinity of Randwick, New South Wales. After his return to Ireland, Mary, Dennis’s wife was born.

Dennis and Mary had five children; Daniel born on March 14, 1860, Mary born in 1866 an died a year later in 1867. Humphrey who was born on December 2, 1867, Jeremiah who was born on March 31, 1870 and John born on April 17, 1873.

After Daniel’s birth Dennis, his wife Mary and little Daniel arrived in the United States in late 1860 and Dennis found work as a butcher. Heading the call for volunteers, Dennis enlisted in the 1st Brigade , 2 Division of the 3rd Army Corps of the 11th Massachusetts Volunteers; in May 1861, being assigned to Company C and mustering in on June 30th. During its initial recruitment it was known as the “Boston Volunteers”, but that was a fairly short-lived name once it was officially designated the 11th Massachusetts. He served for three years during which his unit participated in all major engagements in the Army of Northeast Virginia and with the Army of the Potomac after August 1861. Sullivan was a participant in the Siege of Yorktown, and the Battles of Williamsburg on  May 5th, the Battle of Seven Days at Oak Grove on June 25th, at Glendale on June 30th, was heavily engaged near Groveton on  August 29th  where his regiment led a bayonet charge by the entire brigade against Stonewall Jackson’s line along the railroad embankment, at Malvern Hill, Bristow Station, the Battle of Fredericksburg on December 13th , as a part of Carr’s Brigade, Berry’s Division, Sickles’ 3rd Corps, the 11th lost heavily at Chancellorsville on May 3rd while helping to consolidate the Union defense, it suffered even more at Gettysburg on July 2nd while defending the line of the Emmitsburg Road, just east of the Peach Orchard, the Mine Run campaign suffering casualties at Locust Grove on November 27th, the Battle of the Wilderness on May 5th and 6th,  and others; some fifteen major battles in all, before receiving an honorable discharge in June, 1864.

In 1864 Dennis was again engaged in his profession as a butcher, in Boston, Massachusetts. In 1865, however, he decided to return to Ireland with his wife and their first child, Daniel. Eventually the family left Ireland for Australia, arriving in Melbourne, Victoria in August 1865 aboard the clipper ship “Lightening”;  a splendid vessel 226 feet long with a dining saloon painted pure white, like enamel; owned by Messrs. James Baines & Co., of Liverpool and the largest ship belonging to Liverpool. The “Lightning” was the first ship ever built in the United States for an English house.

Dennis and his family eventually settled down in Eganstown, Victoria where he spent the remainder of his life. The following year, in 1866, their second child Mary Sullivan was born, at Eganstown, but only lived one year; dieing in 1867. Already expecting yet another child, Mary gave birth to her son Humphrey on December 2nd of that same year. Her next child came two years and three months later on March 31st when Humphrey was born; followed by their last son John some three years after that, on April 17th 1873.

Denis Sullivan died on June 23, 1896 at age 60, of liver disease, at Eganstown, Victoria and was buried in the local Roman Catholic Cemetery. The frame constructed Sullivan homestead is said to still be standing today, a preserved  historic structure on the eastern outskirts of Eganstown; 20 miles from Ballarat, Victoria.

In later life Mary Sullivan often walked all the way from Eganstown to Daylesford, to collect her U.S. Army pension check at the post office; which she received through Dennis having served with the Union Army. Upon her death in April 1913, Mary O’Sullivan was buried in the Roman Catholic Cemetery with her husband.

Commissioner of Pensions, Washington, D.C.

Daylesford Historical Society

Department of Records, Killarney, Ireland

M. Cossey, Daylesford, Victoria; Descendant

Massachusetts Regimental Histories

Roman Catholic Cemetery, Eganstown, Victoria

The Clipper Ship Era, Arthur C. Clark,  Riverside CT: 7 C's Press, 1910.