The sentence which is outside the focus of this paragraph is the very last one:
Washington married Martha Custis, a wealthy widow.
The entire paragraph is about the American Revolution, and Washington's involvement in it. His leadership is commended and the outcome of the revolution is revealed.
Even though the last sentence is about him, that is, about who he married, the focus is shifted: from the topic of him as a general, to an extra piece of information about his private life.