The phrase is a variation on a campaign promise Nixon made in 1968: "I pledge to you that we shall have an honorable end to the war in Vietnam.
According to the plan, within sixty days of the ceasefire, the North Vietnamese would release all U.S. prisoners, and all U.S. troops would withdraw from South Vietnam.
[2] Closely connected with the phrase is the idea that Nixon claimed in 1968 to have a secret plan to end the war.
Nixon never made such a claim during his campaign, but neither did he explain how he would achieve peace.
Therefore the assumption that he had a secret plan became a widespread belief and is commonly misattributed as a direct quote.