apply pure justice as in the time of the Caliphs Abu Bakr and ‘Umar, and he set up the Islamic Caliphate on that basis. Those who opposed him and objected to him said that it was impossible because of the great difficulties, and judged according to the Law that they should proceed with relative justice. The other historical reasons are not true reasons, they are pretexts.
As for his war with Mu‘awiya at Siffin, it was a war over the Caliphate and rule. That is to say, Imam ‘Ali gave priority to the injunctions of religion, the truths of Islam, and the hereafter, and sacrificed some of the laws of government and pitiless demands of politics. Whereas Mu‘awiya and his supporters, in order to strengthen Islamic society with their governmental policies, left aside resoluteness and favoured permissiveness; they supposed they were obliged to in the political realm; choosing permissiveness, they fell into error.
As for Hasan and Husain’s struggle against the Umayyads, it was a war between religion and nationalism. That is, the Umayyads founded the Islamic state on Arab nationalism and put the bonds of nationalism before those of Islam, causing harm in two respects:
See, Bukhari, Ahkam, 4; ‘Imara, 36, 37; Abu Da’ud, Sunna, 5; Tirmidhi, Jihad, 28; ‘Ilm, 16; Nasa’i, Bay’a, 26; Ibn Maja, Jihad, 39; Musnad, iv, 69, 70, 199, 204, 205; v, 381; vi, 402, 403.