Having accepted that his original Dalek creations were inherently flawed – primarily, they would not accept his supremacy over them – Davros realised that a new race of Daleks was required to ensure his creation lived on to dominate the known galaxies. In order to ensure their success, Davros determined that he would have to rule them himself; his ego would allow no other solution. All future Daleks would be programmed to obey the Emperor Dakek. Davros was to be the Emperor – ergo, they would obey Davros.
Following the Necros incident, Davros managed to escape from his creations clutches during his trial (aided by The Doctor) and began production of an army in secret on the planet Spiridon. He ensured that each was pre-programmed to obey him as their emperor and began to adopt the title himself. In order to further protect his intellect, Davros began to design and develop a Mark One Travel Machine to new specifications.
During the conquest of Skaro, Davros' mobility chair was destroyed and his underlings quickly constructed a casing based on this design to house the remnants of their emperor. The casing offered far more protection than the mobility chair for Davros' remains but he began to think that only his intellect mattered – his body was a mere shell. In this form, the name Davros slowly fell from use, beginning a spiral of insanity that would ultimately lead to a split personality and the subversion of the Davros identity.
It seems that Davros maintained direct control of all elements of his Empire's development and tactical deployment himself. This burden on his mind may have helped his slide into schizophrenia.
