In 656, Rashidun caliph Uthman was assassinated by an angry mob of muslim pilgrims invading his house. His death sparked a succession crisis, known as the First Fitna, which briefly interrupted the expansion of the Rashidun caliphate, yet led to the creation of the Umayyad caliphate. But what if Uthman had survived, perhaps by sneaking out of the house, perhaps by having more competent guards? I hear that Uthman was preparing his military to besiege Constantinople before his death. Could his planned siege have gone through? And could it have succeeded? Are there any other ramifications?