would distress the European merchants with cotton interests; even so, Seward supported a widespread campaign of public diplomacy. U.S. minister to Britain Charles Francis Adams proved particularly adept and convinced Britain not to openly challenge the Union blockade. The Confederacy purchased several warships from commercial shipbuilders in Britain (, , , , , and some others). The most famous, the , did considerable damage and led to serious postwar disputes. However, public opinion against slavery in Britain created a political liability for British politicians, where the anti-slavery movement was powerful. War loomed in late 1861 between the U.S. and Britain over the Trent affair, which began when U.S. Navy personnel boarded the British ship and seized two Confederate diplomats. However, London and Washington were able to smooth over the problem after Lincoln released the two men. Prince Albert had left his deathbed to issue diplomatic instructions to Lord Lyons during the Trent affair. His request was honored, and, as a result, the British response to the United States was toned down and helped avert the British becoming involved in the war. In 1862, the British government considered mediating between the Union and Confederacy, though even such an offer would have risked war with the United States. British Prime Minister Lord Palmerston reportedly read Uncle Tom's Cabin three times when deciding on what his decision would be. The Union victory in the Battle of Antietam caused the British to delay this decision. The Emancipation Proclamation over time would reinforce the political liability of supporting the Confederacy. Realizing that Washington could not intervene in Mexico as long as the Confederacy controlled Texas, France invaded Mexico in 1861. Washington repeatedly protested France's violation of the Monroe Doctrine. Despite sympathy for the Confederacy, France's seizure of Mexico ultimately deterred it from war with the Union. Confederate offers late in the war to end slavery in return for diplomatic recognition were not seriously considered by London or Paris. After 1863, the Polish revolt against Russia further distracted the European powers and ensured that they would remain neutral. Russia supported the Union, largely because it believed that the U.S. served as a counterbalance to its geopolitical rival, the United Kingdom. In 1863, the Russian Navy's Baltic and Pacific fleets wintered in the American ports of New York and San Francisco, respectively. Eastern theater The Eastern theater refers to the military operations east of the Appalachian Mountains,