What did the Confederacy oppose that made the British not fully support the confederacy ?
It was not anything the Confederacy opposed; but its support of slavery which made the British reticent to support the Confederate cause. From an economic standpoint, the British and Confederacy were engaged in a "marriage of convenience," as the British needed southern cotton to maintain its textile industry, and the Confederacy needed a market for its cotton. General Robert E. Lee invaded Maryland in late 1862 in hopes of demonstrating the strength of the Confederacy to Europe and the British in particular and thereby gaining recognition and support. Lee, of course, lost the Battle of Antietam, so his design was frustrated. Even more significant, however, is that following the battle, President Lincoln issued the Emancipation Proclamation effective January 1, 1863. The Proclamation only freed slaves in those states "in rebellion," but more significantly, forced the British into a moral dilemma: If they supported the South, they would thereby be supporting slavery, which they had outlawed years earlier. It was therefore the slavery issue that made the British reluctant to fully support the South.