In 1946, he founded the Democrat Party along with Adnan Menderes, Fuat Köprülü and Refik Koraltan beginning Turkey's multiparty period, which still goes on to this day.

Mahmut Celâlettin (Bayar after 1934) was born on 16 May 1883 at Umurbey, a village of Gemlik, Bursa,[6] the third son of Abdullah Fehmi Efendi, religious leader and teacher who migrated from Lom, Ottoman Bulgaria as a muhacir, after the Bulgarians ethnically cleansed the Muslim population there during the 1877–1878 Russo-Turkish war.

[7] During his years in Bursa, he attended courses at the Collège Français de l'Assomption, managed by French priests, as well as silk production training at Dârütta‘lîm-i Harîr.

[citation needed] Bayar formed a Unionist militia in Bursa with the intention to join up with Mahmud Shevket Pasha's Action Army during the 31 March Incident.

Bayar established an organization and CUP mouthpiece known as Halkın Doğru (True to the People), where he wrote pro-CUP articles under the pseudonym Turgut Alp.

[12] Well connected with financial circles, Bayar played an important role in Unionist Millî İktisat (National Economy) policies.

However, when the allied powers continued advancing into Ottoman territory despite the armistice, various nationalist organizations known as Defence of National Rights Associations started to be founded.

Bayar fled into the mountains after hearing rumors of an impending allied occupation of İzmir and finding out his name was on an arrest list from the Freedom and Accord government in Constantinople.

Following the occupation of Constantinople, he fled to Ankara to join Mustafa Kemal (Atatürk) Pasha and the Turkish Independence Movement.

[18] Bayar was influential in determining the economic policy of the regime as a result of being in Mustafa Kemal's close circle during this period.

On 26 August 1924, Atatürk commissioned Bayar to found a national bank, which resulted in the foundation of İşbank[19] in Ankara by using as capital the gold bullion sent by the Muslims in India to support the Turkish War of Independence.

The Aşar tax was abolished, land was distributed, the Teşvik-i Sanayi Kanunu (Industry Incentive Law) was enacted, railway construction was accelerated, and the Central Bank was established.

Bayar's term as economic minister saw an increase in regulatory interventions in the economy by the state, and high levels of industrialization.

The end of World War II brought about a global wave of democracy, which resumed the power struggle in the one-party regime between the two versions of statism espoused by İnönü and Bayar.

The motion demanded political liberalization in the country and in the party, but was soundly rejected by the members of the CHP Central Council.

[4] The party program of the DP featured Bayar style approaches to economic policy, political democratization, decreasing the power of the bureaucracy, and encouraging private initiative while maintaining the principle of statism.

During Bayar's presidency relations with the Western bloc improved and after the Turkish Straits Crisis, Turkey joined the Korean War in 1951[22] and then NATO in February 1952.

In the second half of the 1950s, with the impact of the economic depression, the DP pursued increasingly authoritarian policies and put heavy pressure on the opposition.

Bayar first tried to resist the officers who came to arrest him at Çankaya Mansion on the morning of the coup and then tried to commit suicide by holding the pistol in his jacket pocket to his temple.

The National Unity Committee approved the death sentence for Menderes, Zorlu, and Polatkan, but the punishment for Bayar and other twelve party members was commuted to life imprisonment.

Under pressure from ex-DP supporters, Bayar's sentence was suspended by the government for a period of six months due to his health issues and he was released on 22 March 1963.

[25] With a new amnesty law enacted by the Justice Party government on 8 August 1966, all former DP members, including those sentenced to life imprisonment, were freed.

In 1968, he founded a club called Bizim Ev (Our Home), which aimed to bring together ex-Democrats who lost their political rights.

He held a historic meeting with his political rival İnönü on 14 May 1969 that lead to CHP passing a constitutional amendment which returned suspended rights to former DP members.

Full political rights were restored to Bayar in 1974, but he declined an invitation to become a life member of the Senate, on the grounds that one can represent the people only if elected.

[29] From 24 April 1978, when former Paraguayan President Federico Chávez died, until his own death Bayar was the world's oldest living former head of state.

27 January 1954 Bayar received the Legion of Merit Award from the President of the United States, as a result of Turkey's participation in the Korean War.