His only apparent support in the Army was Yazid bin Muhallab, who was in Suleyman's debt from the days when the latter's elder Brother al-Walid was reigning (Yazid was imprisoned and tortured by Hejaj bin Yusuf and was safe only after Suleyman interceded on his behalf, making the Caliph order Hijaj to cease his attempts at murdering Yazid).
But on the other hand we see other senior generals of the Army like:
- Hijaj bin Yusuf, opposed Suleyman's appointment as heir apparent and advocated succession of al-Walid's sons instead. One of the most loyal servants the Umayyad dynasty ever had, it's curious that he most vehemently opposed Suleyman Umayyad and was so frightened by the prospect of his ascension that he wished not to outlive Caliph Walid.
- Muhammad bin Qasim, followed his uncle Hijaj and refused to accept Suleyman as the rightful Caliph.
- Qutayba ibn Muslim, opposed Suleyman's appointment as heir apparent and advocated rights of al-Walid's sons instead.
- Musa bin Nusayr, views on Suleyman's appointment unknown but held him in little regard as evident by the fact that even though Suleyman ordered him to hold off the triumph parade to celebrate conquest of Spain for a few days so that ailing Caliph Walid could die and Suleyman's reign would begin with victory parades and news of victory in the West, Musa refused to do so and held the parade and presented the plunder to the dying Caliph.
- Tariq bin Ziyad, same case as Musa bin Nusayr.
Suleyman, for all his flaws, proved to be a capable ruler. Walid's sons on the other hand, Yazid III and Ibrahim, proved to be very ineffectual in their short reigns (But of course we have the benefit of hindsight which the Walidist Generals did not enjoy - Still it's unlikely that a shrewd Politician like Hijaj messed up in getting the right measure of the Princelings). Suleyman never forgot those men and all of them lost their stations and many their lives for opposing his succession and other offences.
What was it about Suleyman that the most generals disliked? Why is that the most loyal of the Umayyad dynasty's officers felt more loyalty to al-Walid and his sons than to Suleyman?
It is very likely that his short temper may have been part of the reason but I find it very bizarre for the bureaucracy to be against a ruler just because he was bad tempered. A lot of Kings and Emperors used to be very rash and prickly. It wouldn't be the first time either in history of Caliphs. When Caliph Abu Bakir appointed Umer as his successor, a lot of Generals and Officials voiced their concerns that he was short-tempered and strict. Abu Bakr's only reply was that burden of ruling would soften him up. Umar never faced opposition from the army like that. (But of course Umer was one of the leading Companions of the Prophet and therefore commanded respect of most of the people, Suleyman wasn't and didn't.)