George Washington
At the end of his second term, Washington retired for personal and political reasons, fatigued and disgusted with personal attacks, and to assure a truly contested presidential election could be held. He did not feel bound to a two-term limit, but his retirement ultimately set precedent. The two-term limit to the presidency was formalized with the 1951 adoption of the Twenty-second Amendment to the United States Constitution. Washington is often credited with setting the principal of a two-term presidency, but it was Thomas Jefferson who first refused to run for a third term on political grounds.
2015 Republic of the Congo constitutional referendum
After Denis Sassou Nguesso returned to power in the 1997 civil war, a new constitution was approved in the January 2002 constitutional referendum. The 2002 constitution provided for a strong executive presidency, without a prime minister, and weakened the legislature; the length of presidential terms was increased to seven years (with a limit of two terms), and an age limit of 70 years for presidential candidates was established, apparently to exclude Sassou Nguesso's most important political opponents, who had either reached that age or were nearing it. Parties opposed to Sassou Nguesso criticized the new constitution and called for the people to boycott the 2002 referendum.