AKA For Want of a Nail : If Burgoyne Had Won At Saratoga.
A famous and highly influential alternate history novel, written in mock-textbook style by business historian Robert Sobel in 1973. Regarded as one of the finest and most influential works of the alternate history genre. The title comes from the well-known proverb that embodies the “what if something changed and influenced the outcome” approach of thinking that is the basis for alternate history.
DBWI: The "For Want of a Nail" Discussion Thread - Double blind what if POD discussion, reimagining the contents of the novel in an ATL.
A rough timeline summary of the novel
Sobel Wikia - A nice and detailed Wiki project, founded by fans of the novel and former soc.history.what-if members.
For Want of A Nail entry on Uchronia.net
For All Nails - A timeline continuation and clarification project created by the novel's fanbase. Also here.