By 1961 the Action Group was split between Chief Obafemi Awolowo — federal Leader of Opposition, advocating a socialist 'democratic socialism' platform — and his Deputy Chief Samuel Ladoke Akintola, Premier of the Western Region, who preferred accommodation with Tafawa Balewa's NPC-NCNC coalition. The Jos Congress of February 1962 endorsed Awolowo's line and removed Akintola as Deputy Leader. Akintola refused to resign as Premier.
On 25 May 1962 the Western House of Assembly descended into a brawl: the Speaker's mace was used as a weapon, chairs were thrown, the Igbira Sergeant-at-Arms broke up the sitting. Federal Prime Minister Balewa declared a State of Emergency on 29 May 1962 — the first in Nigeria's history — suspended the Western Region government for six months, appointed Dr Moses Majekodunmi as Sole Administrator, and restricted Awolowo to Lekki Beach.
The Coker Commission (October 1962) inquired into the finances of six Action-Group-controlled corporations (the National Investment & Properties Co., the Nigerian Property & Investment Co., and four others) and found that £6.7m had been illegally diverted from the Western Regional Marketing Board through Awolowo associates to fund the Action Group's federal campaign. On 2 November 1962 Awolowo and 26 others were arrested for treasonable felony; the September 1963 trial before Justice George Sowemimo convicted Awolowo and sentenced him to ten years' imprisonment.
Akintola — restored as Premier of the new United People's Party / Nigerian National Democratic Party — went on to rig the October 1965 Western Region election that produced Operation Wetie. The constitutional crisis, the imprisonment of the Yoruba Leader, and the breakdown of inter-party trust supplied the political pretext for the 15 January 1966 coup in which Akintola was killed. The 1962 crisis is the pivot on which the First Republic collapsed.