The expansion of the hospital, which Steuart considered his life's work, was authorized by the Maryland legislature in the 1850s and completed after the end of the Civil War.

At the start of the American Civil War, Steuart was relieved of his position as superintendent of the hospital because he refused to sign an oath of loyalty to the Union.

Spring Grove continues to treat mental illness in the 21st century, and is the second oldest institution of its kind in the United States.

Through his sister, Elizabeth Sprigg Steuart (1803-1896), he was the uncle of Charles William Kinsey (1829-1883), who served as a Virginia Congressman from 1882 to 1883, and was a Major in the Confederate Army, who was a friend of Gen. Stonewall Jackson, and was present at his death.

He served at the Battle of North Point on September 12, 1814, where the Maryland Militia were able to hold off a British attack long enough to shore up the defense of Baltimore.

[7] By 1853 he was described by the American Journal of the Medical Sciences as "well known as one of the most eminent physicians of this city [of Baltimore]",[8] Steuart's most notable contribution to the field of mental illness was his work for the Maryland Hospital for the Insane (founded in 1797).

By the mid-nineteenth century, the hospital's bed capacity was no longer adequate, and Steuart managed to obtain authorization and funding from the Maryland General Assembly for the construction of a new, larger facility at Spring Grove.

As a result, Steuart gave up his general medical practice, after what he described as "23 years of hard professional life,"[13] in order to concentrate on managing his new plantation.

From 1828 Steuart had served on the Board of Managers of the Maryland State Colonization Society, of which Charles Carroll of Carrollton, one of the co-signers of the Declaration of Independence, was president.

Steuart wrote: Steuart was among those who lobbied Governor Hicks to summon the state Legislature to vote on secession, following Hicks to Annapolis with a number of fellow citizens: The political situation remained uncertain until May 13, 1861 when Union troops occupied the state, restoring order and preventing a vote in favour of Southern secession, and by late summer Maryland was firmly in the hands of Union soldiers.

[22] The family's Baltimore residence, Maryland Square, was seized by the Union Army and Jarvis Hospital was soon erected on the grounds of the estate, to care for Federal wounded.

[23] Dodon was not confiscated by the Union but, during the course of the war, horses were raised and trained and then smuggled south for Confederate forces, as well as medical supplies such as quinine.

[9] However, he was once again removed in 1875 when the board, under his leadership, mortgaged the hospital to a group of private investors, after the Maryland Legislature had failed to fully fund its operations.

[9] Spring Grove continues to treat psychiatric illness to this day, and is the second oldest institution of its kind in the United States.