Let's go back to the early years of the Republic. In 1912, Sun Yat-sen was elected first provisional president. In hopes of encouraging the "last emperor" of the Qing dynasty, Pu Yi, to peacefully abdicate, Sun struck a deal with Yuan Shikai, a Qing military leader, that Sun would give up his position to Yuan if Yuan forced Pu Yi to step down.
話說民國初年，甫當選中華民國臨時大總統的孫中山先生，為了希望早日迫使北方的清帝溥儀和平退位，和當時的清廷內閣大臣袁世凱定約，只要袁世凱能逼退溥儀，孫中山即「讓位」給袁世凱。