The beginning of an alliance
In the fall of 1861 the British packet ship Trent was bombed by the American ship USS San Jacinto. The bombing was allegedly accidental and was supposedly ordered in haste as the Trent was transporting two Confederate politicians to England namely James Mason of Virginia and John Slidell of Louisiana who were on a diplomatic mission. The US government refused to apologise and even presented its actions as defensive against British intrusion into American affairs.
The Government of Great Britain bided its time but played on the feelings of its populace as Lord Palmerston and Russell constantly voiced disapproval of the USA and its aggressive behaviour. Considering how economically valuable the USA was to Britain they did nothing until the late summer of 1862 when the Union was in trouble as it lost the second battle of Bull Run. Palmerston now began publicly offering to mediate the conflict, his offers were of course sharply rebuffed, however in the May of 1863 Union troops under the lead of Joseph Hooker suffered a major defeat at the Battle of Chancellorsville, Virginia. Pressure now mounted on Lincoln from the American upper classes to make peace with the CSA. Two months later Lincoln resigned the presidency and the war was all but over the peace of London signed in August of 1863 confirmed this.
The war had ended in a truce in real terms however this was very much a victory for the Confederates who had freed themselves from northern rule and subordination to Washington. Britain and the CSA were now strongly linked and whilst not formal Allies there economies became more and more intertwined. The USA meanwhile moved further towards France, a vocal critic of the CSA dues to its practice of slavery and new found economic friendliness towards the UK. The world slowly divided into two camps as the UK also grew to support Prussia and other states against french foreign policy aims and objectives.
The next 150 years would be shaped by the shadow of the Confederate-British alliance formalised by the Ottawa accords signed in 1879. Our world today is the result of this great transatlantic pact.