Why do major parties pick their candidates for president of the u. s.?

In primaries, party members vote in a state election for the candidate they want to represent them in the general election. After the primaries and caucuses, each major party, Democrat and Republican, holds a national convention to select a Presidential nominee. ... On election day, people in every state cast their vote .

Explanation:

haitian revolution slaves initiated the rebellion in 1791 and by 1803 they had succeeded in ending not just slavery but french control over the colony

it would be  

germany had to pay all damages related to the war.

and i think

germany had to take sole responsibility for the war.