Before Andrew Jackson became the 7th president of the US, he was a general in the Army. The Creeks were a tribe of indians that lived in Alabama and Georgia. On August 30, 1813, a small group of the Creeks attacked some Alabama settlers killing 250 of them. This resulted in the Creek War (1813-1814) in which General Jackson's troops, among others, eventually defeated the Creeks and they were forced to give up their land-- 3/5 of Alabama and 1/5 of Georgia--sending them "up the creek".
As a result, other settlers, like Simon Finch, were able to move to Alabama. The next paragraph in the book explains how Simon Finch is related to the Finchs in the book and how he came to settle where they live now. If General Jackson hadn't defeated the Creeks they probably wouldn't be living where they are now.
