The one that declared that slavery was necessary was John C. Calhoun.
He was a US South Senator.
He was a political leader. He was a congressman, a secretary of war, a vice president, a senator, and a secretary of state. He believed that slavery was a symbol of the south and that it was something possitive.
The Zimmerman telegram was a message sent by Germany to MEXICO to cripple a few of their states in 1917 during the first world war. The transmission never reached mexico however and was intercepted by British inelegance.
I believe it is a means to harvest the area of all timber, which can be beneficial for economic reasons and the ecosystem
George Washington is the first president