Born in New Orleans, he was known as a "volcanic Creole". During the American Civil War, he served in Company A. Withers' Light Artillery (in Carter L. Stevenson's division), as a Private at the Siege of Vicksburg. In September, 1862 he was discharged from the army on account of sickness and being unable to return to his home, New Orleans, obtained a position in the office of the Vicksburg Whig where he remained until its destruction by fire in the early part of May 1863, and was taken prisoner and paroled after the surrender when he moved on briefly to Mobile, Alabama, then to Atlanta where he quickly settled. At first in Atlanta he was associated with Jared Whitaker's Daily Intelligencer and using their presses published in late 1863 an eighty-page description of Vicksburg's capture and then a novel called The Trials of the Soldier's Wife. In 1864, he again soldiered to protect a city under siege, this time Atlanta and fought the Battle of Jonesboro where he was wounded and no longer fit to bear arms.
After the war, he took the loyalty oath and in December 1865 he moved to New York City with his wife and infant son to join the New York Herald. There he was schooled by the best, editor James Gordon Bennett, Sr., and promoted quickly through the ranks. By 1870, he was the foreign editor and handled all dispatches from the Franco-Prussian War. By the time of the surrender at the Battle of Sedan, he maintained rooms at the Astor House across the street from the Herald to receive encrypted dispatches to which he held the only key.
At this point his health broke and James Gordon Bennett, Jr. offered him positions in either California or Georgia. He chose Georgia and moved back with his family where his wife owned printing equipment stored on Forsyth St. which he used to found the Daily Herald. Soon after Robert Alston and Henry W. Grady joined the business; Abrams was managing editor, Grady was general editor and Alston the business manager.
Abrams' writing apparently never caught on in Atlanta which Grady explained by saying he had a certain coldness that "in small cities, there must be provincial touches in the journal – concessions that the journalist must make to circumstances" and when he ended up running the Atlanta Constitution, Grady made sure his personality shined unlike his former colleague. But back in 1872, Abrams maintained a feud with former governor Joseph E. Brown, denouncing the policy of the state leasing the Western and Atlantic Railroad and associated business deals with free rides but was pressured to relinquish control of the paper with a threatened foreclosure of a $5,000 mortgage by Citizens Bank unless he ceased the attacks on Brown. He sold his interests and moved south.
In Florida, he was a prominent lawyer representing large companies such as Seaboard Air Line Railroad.
As a reward for his successful efforts to elect the first Democratic governor and legislature since the end of the US Civil War, St. Clair-Abrams was appointed state attorney for the Seventh Judicial Circuit.
St. Clair-Abrams founded Tavares, Florida, in 1880 and hoped to make it the state capital, and while that didn't happen, in 1887 it was made the seat of Lake County.
In Tavares St. Clair-Abrams constructed a sawmill, hotel, office building, and opera house. In 1883 two companies he was a part-owner of — Peninsular Land, Transportation and Manufacturing Company and the Tavares, Orlando and Atlantic Railroad — were chartered by the state.
St. Clair-Abrams was instrumental in the creation of Lake County from parts of Orange and Sumter counties in May 1887.
In 1892 St. Clair-Abrams was elected to the Florida senate. However he resigned the office in 1893 because of a controversy that resulted over the location of the Lake County courthouse.
In 1895 St. Clair-Abrams moved to Jacksonville.
By 1897, Abrams, Sr. was in Jacksonville where he successfully defended Edward Pitzer in the murder trial of Louise Gato in dramatic fashion (he fainted while making his concluding statement). His home there was built in 1914 and designed by Henry John Klutho, it was placed on the National Register of Historic Places in 1985. Abrams wife died in Atlanta in late 1901, her remains were dispatched to Jacksonville where he built a family mausoleum in the St. Mary's section of Evergreen Cemetery that was designed by Klutho in 1901. In 1914, he argued before the United States Supreme Court in Florida East Coast R. CO. v. U S, 234 U.S. 167.
In 1928, he described himself in a letter to the Constitution as "84 years of age, feeble and crippled, but with my mental faculties unimpaired". He died in Jacksonville in 1931 at the age of 86.
His only son Alfred was prosecuting attorney of Lake County when he surrendered after the shooting death of railroad man, W. Bailey Tucker. Alfred St. Clair-Abrams was running for the state legislature as an anti railroad candidate, and he believed that Tucker had brought about his defeat by unfair means. Alfred shot Tucker in the head with a shot gun loaded with buckshot. Alfred was freed and later that year sought a divorce from his wife who had had an affair with Tucker and another man.In 1887, the Dickson Manufacturing Company named a 4-4-0 locomotive with serial number 574 after Abrams.
The major perpendicular road to Main Street in downtown Tavares is named St Clair Abrams Ave
His Great Floridian plaque is located at the St. Clair-Abrams House, 305 New Hampshire Avenue, Tavares
Alexander St. Clair-Abrams House, 1649 Osceola St., Jacksonville
Works by Alexander St. Clair-Abrams at Project Gutenberg
Full and Detailed History of the Siege of Vicksburg (1863), Intelligencer Steam Power Presses, Atlanta
The Trials of the Soldier's Wife: A Tale of the Second American Revolution (1864), Intelligencer Steam Power Presses, Atlanta
Manual and Biographic Register of the State of Georgia, 1871-1872 (1872), Plantation Press, Atlanta