Paying rich tributes to India's first home minister Sardar Vallabhbhai Patel on his birth anniversary, Singh recalled that Hyderabad State merged with the Indian Union more than a year after Independence.
Singh flagged off the 'Run for Unity' and participated in the passing out parade of Indian Police Service Officers at Sardar Vallabhbhai Patel National Police Academy here.
He said it was because of the foresightedness of Patel that Hyderabad became part of India.
Singh said Patel single-handedly achieved the merger of 562 princely states into the Indian Union in 70 days with minimum violence and maximum willingness.
"If one person is to get credit for shaping the geography of India as we see it today, it should go to Sardar Vallabhbhai Patel," he said at the passing out parade of trainee police officers.
He noted that after 10 years the academy is holding the passing out parade on Patel's birth anniversary and asked the academy director to ensure that the parade is held every year on this day.
The home minister said Prime Minister Narendra Modi has decided to observe Patel's birth anniversary as 'National Unity Day'.
At both the events, Singh administered the unity day pledge to the gathering.
Earlier, he flagged off the run after paying tributes to Patel at his statue near the assembly building.
A large number of people, majority of them BJP workers, participated in the run. Many of them held the national flag in their hands.
BJP Telangana unit president G. Kishan Reddy, party MP Bandaru Dattatreya and actor Krishnam Raju were also present on the occasion.