Final answer:
Zimmermann mentioned peace with the British to encourage Mexico to attack the U.S., creating a diversion that could enable Germany to compel England to make peace.
Step-by-step explanation:
The mention of the prospect of peace with the British by Zimmermann was aimed at enticing Mexico to join Germany's side during World War I by attacking the United States, should America enter the war against Germany. Zimmermann's goal was to distract the U.S. and thus reduce the pressure on Germany, allowing them to gain the upper hand in Europe. The Zimmermann Telegram significantly shifted public opinion in the United States and provided President Woodrow Wilson with the support necessary to sever diplomatic ties with Germany. This eventually led Congress to declare war on Germany in April 1917.