New York City's Governor Horatio Seymour and other Northern Democratic Party leaders certainly did have a hand in provoking the New York City Draft Riot of 1863, the "bloodiest outbreak of civil disorder in American history" ("On This Day," The Learning Network, The New York Times). Governor Seymour was one of the nation's Peace Democrat leaders. Peace Democrats were Northern Democrats who opposed the Civil War. Peace Democrats especially represented the working class Irish and German populations of New York City who feared slave emancipation would cost them their jobs. At the beginning of Abraham Lincoln's first term as President, Northern Democrats warned the working class that emancipation would enable freed slaves to move north and take over the labor force ("Copperhead," Encyclopaedia Britannica).
After the Emancipation Proclamation was issued in 1863, Northern Democratic leaders of New York City began "distributing pamphlets and organizing public rallies" and declaring public warfare against the "war, emancipation, blacks, Lincoln and Republicans." These protests began months before the anti-draft riot of 1863 ("On This Day"). In addition, Governor Seymour, acting as the leading voice against the draft, publicly warned the "bloody and treasonable and revolutionary doctrine of public necessity can be proclaimed by a mob as well as by a government" ("On This Day"). We can interpret Governor Seymour's words of warning as playing a major role in instigating the New York City riot.
Regardless of protests against the draft, the need for more men in the military was becoming increasingly urgent. Due to substantial losses in the Battle of Gettysburg, fought between July 1st to July 3rd of 1863, New York City had been left with no more than 550 men to defend 8 forts and not one single naval ship to defend its harbor, prompting a draft lottery to begin on July 11th, 1863. By July 13th, hundreds of white working-class men began marching in protest. The outbreak of violence resulted in the draft office being torched, an army squadron being forced to retreat, a police officer being brutally assaulted, telegraph poles being downed, train tracks being uprooted, homes of wealthy Republicans being attacked and looted, the city's arsenal being torched, the homes of African Americans on the west side of the city being torched, black laborers being lynched and torched, and many other bloody casualties ("On This Day").
The riot began at 6 AM on July 13th, and Governor Seymour is reported as having done little to end it. Reports say he tried to "negotiate with rioters," addressing them as "My friends" and promising to repeal the draft ("On This Day"). After Confederate General Robert E. Lee moved his soldiers to Virginia in retreat on July 4th, Lincoln's Secretary of War, Edwin McMasters Stanton, was able to send 5 regiments to New York City to put an end to the riot; troops did not arrive until July 15th. Fighting between soldiers and rioters lasted until the evening of July 16th, and the consequences of the riot were about 115 deaths, including a dozen African Americans, and millions of dollars of damage to the city.
Since Governor Seymour did little to end the riot, especially when it first began, and continued to fuel anti-war and anti-draft sentiments, it can be argued Seymour was a key instigator of the riot.
In addition, historians report Seymour as having written a letter to President Lincoln on June 30th that warned there would be a riot if Lincoln proceeded with the draft. Furthermore, historians report James R. Gilmore as investigating the instigators of the riot after it was crushed and reporting to Lincoln with knowledge learned from General Richard Busteed that the "riot was planned and set afoot by Govr Seymour, Fernando Wood [previous mayor of New York City], and a small coterie of leaders of their stripe" ("Response to Riots," The Lehrman Institute, Mr. Lincoln and New York).