The action of Umar according to Taha Hussein

....Umar was assassinated in the 23rd year of the Hegira, not even a quarter of a century after the foundation of the State. This short interval of time had not passed in peace and stability. On the contrary, it had taken ten years to win the Arabs to Islam, a little more than a year to reconvert the Renegades, and the rest of the time to propagate the religion beyond the territory, that is, fighting the Persians and driving the Byzantines from Syria and Egypt, then to govern these provinces, raise armies and to put in place policies for war and peace, and an administration of domestic and foreign affairs........the first two caliphs together created solutions in a Bedouin society with no history of administration, politics, or civilisation in general. Not only did they they create this but they imposed discipline on a people who were unaccustomed to it and attempted to inculcate into them the rudiments of civilisation. Umar in particular made great efforts in this regard. Hardly had he discovered an aspect of the civilisation of other countries, than he studied it in order to adapt it to the Arab temperament, to Islam, and to the nascent state whose growth and expansion soom surpassed the plans of thinkers and the know-how of the men of action.

As for the second constituent element of this regime – the leadership of the Companions – it was destined to disappear with time and the arrival of new generations who no longer had their distinction. They should have been given a system which secured the way of being a Caliph, to control, to punish if need be. Endowed with such a system, the Muslims would have been able to avoid the discord which followed the assassination of Uthman: some – the Kharijites – fiercely defended the Tradition of the Prophet and the first two caliphs; others demanded that the Caliphate be reserved exclusively for the Prophet's house; a third group opted for a path to monarchy on the lines of the Persians or the Byzantines; finally a fourth urged a regime based on consultation without knowing how this worked......the first two caliphs and their friends lacked the time for development, and contacts with civilised life, indispensable factors in building the desired system. The next generation did benefit from favourable conditions, but far from taking advantage of them, they let themselves be seduced by pride and the splendour of power.

Source: Taha Hussein, La Grande Épreuve. 'Uthman, Paris, Vrin, 'Etudes musulmanes' 1974, p31-32