The Great Coalition was a grand coalition of the political parties of the two Canadas (Upper and Lower, or more legally, West and East) in 1864. The previous collapse after only three months of a coalition government formed by George-Étienne Cartier, George Brown and John A. MacDonald. The Great Coalition was formed to stop the political deadlock between predominantly French-speaking Canada East and predominantly English-speaking Canada West. The government at that time was unable to pass anything because of the need for a double majority. In order for a bill to pass in the Legislative Assembly, there had to be a vote in both Canada East and Canada West sections of the assembly. The French and the English could never agree on anything; this caused the political deadlock.
The removal of the deadlock resulted in three conferences that led to confederation. The Charlottetown Conference, was intended for politicians to discuss the idea of a Maritime union. They chose to expand their talk to the colony of Canada, and took the opportunity to discuss the possibility of a larger union that would include all of British North America. The Quebec Conference was to further discuss the union of British North America and to define the details of what shape that government would take. They settled on Provincial and Federal responsibilities and got approval from the Queen. The London Conference was to refine The Quebec Resolutions.
All of these events led to Canada's existence on July 1, 1867.