Confederacy uses tanks

At the time of the Crimean War a British inventor designed the world's first tank: a steam tractor armed with cannons and protected by dome-shaped armor plate similar to that of Da Vinci's war machine. The British rejected his design so a decade later the inventor took it to America. The Confederacy, aware the Yankees were more numerous and better equipped, decide to put the tanks into production in the hope of tipping the balance. A British police raid on a Laird Bros shipyard at Birkenhead reveals components for these tanks are being constructed there for final assembly in America. Several of these vehicles are confiscated by the Royal Navy for testing but elsewhere production secretly continues uninterrupted.
How would these armored steam tractors have affected the war? What effect would they have on northern morale? Would the South win? Would the North fall? Would other countries intervene? How would this affect the various empires? And would these steam vehicles kickstart an arms race among the European nations resulting in a Steampunk-type world?

Hard to say....shock and mobility are amplified by speed and ability to negotiate terrain.....any stats on the anticipated ROM of the beast?

Britain used armoured tractors during the Crimean War, but the lack of adoption of this design cast doubts on how well it worked. The Mark I barely worked 60 years later.

The Victorians had a solution for difficult terrain long before caterpillar tracks were invented. Early road locomotives were often fitted with "footed wheels:" flexible wooden boards that enabled the steam tractor to climb steep hills and cross muddy ground

Absolutely. Steam tractors were slow and unwieldy machines: good for pulling heavy loads but difficult to steer

They did. In addition to using captured Gatling Guns the Confederates had a primitive volley gun similar to the Mitrailleuse and a rapid-firing cannon called the Williams Gun
Artilleryman magazine