why did smalltime rulers &chieftans support the sepoys
Answers
The Rebellion of 1857 started in a big way on 10th May, 1857 in Meerut, the largest cantonment of the British in India, with a significant number of native soldiers (called Sepoys by the British, as an anglicized word for Sipahi) rebelling.
The logical escape for the rebels was Delhi, which was only 40 miles away from Meerut and was a strong walled city. There were no British troops in garrison there in contrast to Meerut. Delhi was also the present seat of the Mughal Emperor, Bahadur Shah Zafar. Though he was a senile figure aided by a restricted pension by the British East India Company, he was still an emperor, an heir of the Mughal Empire that was one of the greatest in history of India. Reluctantly, Zafar accepted the rebels' allegiance and agreed to give his countenance to the rebellion. At this point, there was no trouble in Jhansi, and Rani of Jhansi had no plans of joining the rebellion.
It took the British over a month to muster resources and begin the siege of Delhi and heavy bombardment went on till September when they overtook the city and Zafar surrendered. Around September-October, trouble fomented in Jhansi fort, and events led the Rani to jump in.
Note that the rebellion wasn’t very organized and events took place in silos in places like Meerut, Delhi, Kanpur (called Cawnpore by the British), Jhansi, Lucknow, Gwalior.
Besides being first in timeline, Bahadur Shah Zafar was a logical choice to be proclaimed as Emperor of India. He was relatively neutral towards religion, hence Hindu rebels had no issues accepting him as the leader. Overall, there was little unity among the rebels - there was a faction that wanted the Maratha rulers to be enthroned, Awadhis wanted to reclaim the powers that their Nawabs used to have, there was tension within Muslims due to the Shia-Sunni divide. There were calls for Jihad, but Zafar resisted these calls as he feared outbreak of communal violence within the native population. The Sikhs were not ok with Zafar’s leadership as that would have meant return of the Mughal Empire, and they had bad history with how their Gurus were treated by former Mughal Emperors. They sided with the British.
Given the prestige held by Bahadur Shah Zafar, he became the logical choice when the rebellion started. After his surrender in September 1857, the rebellion continued till November of 1858 when it was completely put down. Post Zafar, there were regional leaders fighting out with their forces or helping out other leaders, but there was no central command figure.