In which year, did the last Chinese Emperor of Ming dynasty commit suicide at the age of 33 years?

The Chongzhen Emperor (27 January 1611---25 April 1644) was the 17th and last Emperor of the Ming dynasty. He reigned from 2nd October 1627 to 25th April 1644. He allegedly hanged himself from the 'pagoda' tree (Styphnolobium japonicum) on 25th April 1644 in Jingshun Park, Beizing, China. The original tree was replaced numerous times. The current one is a 150 years old replacement and replanted in 1996. It is a tourist attraction and a national landmark in Jingshun Park.

The Chongzhen battled peasant rebellions led by Li Zicheng (22 September 1606---1645) and was not able to defend the northern frontier against the Manchu, an ethnic minority in China. The Manchu formed the succeding Qing Dynasty. The Chongzhen Emperor walked to a small hill in present-day Jinshun Park to commit suicide, which is an imperial park covering 23 hectares (57 acres) immediately north of the forbidden city in the imperial city area of Beijing,China.

Li Zicheng offered the Emperor an opportunity to surrender and summoned his forces to attack on 24 April. The Chonzhen Emperor held his last audience with his ministers on 23 April. He gathered all members of the imperial household except his sons. He killed Consort Yuan and Princess Zhaoren using his sword and severed the arm of Princess Changping. The Emperor was buried in the Ming tombs, a collection of mausoleums built by the emperors of the Ming dynasty of China.