Short answers, pulled from the story.
The Confederate envoys captured during the Trent Affair were John Slidell of Louisiana and James Murray Mason of Virginia. They had been selected by President Jefferson Davis to open diplomatic relations with European powers.
Captain Charles Wilkes captured the British mail packet Trent on the 8th of November 1861. The incident occurred in the narrow Bahama Channel after lookouts aboard the U.S. Navy frigate San Jacinto spotted the vessel unfurling its Union Jack.
The United States released the Confederate envoys to avoid a serious conflict with Britain and prevent financial collapse. Treasury Secretary Salmon P. Chase felt that releasing the prisoners was necessary to support the economy while preserving American sovereignty.
Great Britain sent eleven thousand troops using eighteen transport ships during December 1861. By the end of the month reinforcements had raised the count to nine hundred twenty-four officers and seventeen thousand six hundred fifty-eight men.
Mason and Slidell resumed their voyage to Europe on the 10th of January 1862. President Lincoln released the envoys and disavowed Captain Wilkes' actions without a formal apology to resolve the crisis.