Having handled the administration of Tamil Nadu during this crucial phase - which saw a turmoil in the ruling AIADMK following its supremo J Jayalalithaa's death, Rao described the situation post her demise as "delicate".
"These 13 months (September 2016-September 2017) were essentially the most critical months in the political history of Tamil Nadu and its people," he said.
Rao was speaking at the Raj Bhavan here, where Vice President M Venkaiah Naidu released a book that records Rao's tenure. The book is titled 'Those Eventful Days'.
He said things were "perfectly normal" till Jayalalithaa was hospitalised on September 22, following which a "number of political developments took place."
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"The situation in the state was very delicate following the demise of Selvi (Ms) Jayalalithaa. To the credit of the political leadership, the state administration and the state police, the situation was handled extremely well," Rao said.
He said he has the "highest regard" for Jayalalithaa, who had received him at the airport when he arrived here to take charge last year.
"I have had excellent relations with leaders of the ruling party. There (have been) occasions where the opposition leaders disagreed with me. But they never disrespected me," he said.
Rao, without referring to any instance, however, said "restraint should not be misunderstood."
"Avvaiyar (Tamil poet) had said restraint should not be misunderstood. We all are supposed to have self-restraint. That is the culture of this country," he added.
"Quite often editorials in newspapers provided me with solutions to some of the trickiest situations the state faced during the troubled phase," he said.
According to a press release, the book on Rao captures his tenure in 12 episodes. The first chapter portrays his "cherished moments" with Jayalalithaa.
The second chapter reflects on the Constitutional deadlock that arose after Jayalalithaa's hospitalisation.