How does the author use foreshadowing in Washington, the Indispensable Man?

Washington, the Indispensable Man is a nonfiction book, thus, it does not use forehadowing. Flexner, however, notes that Washington's signing of a peace document on July 4, 1754, a treaty that ended the altercation with the French in the Ohio Valley, foreshadowed his signature on the Declaration of Independence.