Her claim comes amid the controversy over RSS chief Mohan Bhagwat's remarks on the Army.
While speaking to reporters, Ms Bharti refused to make a direct comment on Mr Bhagwat's remarks.
However, she said soon after independence, Maharaja Hari Singh, the ruler of the princely state of Kashmir, was not signing the accession treaty of Jammu and Kashmir and Sheikh Abdullah was pressing him to sign.
"Nehru was in a dilemma. Then Pakistan suddenly attacked and its soldiers advanced upto Udhampur," she said.
The Army did not have "hi-tech equipment" to reach there immediately as the attack was unexpected, the Union minister said.
"At that time, Nehru-Ji wrote a letter to Guru Golwalkar (then RSS chief MS Golwalkar) seeking RSS volunteers' help.
RSS volunteers went to Jammu and Kashmir to help," Ms Bharti claimed.
The opposition parties had on Monday charged Mr Bhagwat with "insulting" the armed forces and the country by claiming that in the eventuality of a battle to be fought, the RSS could mobilise itself in three days while the Indian Army would take six to seven months to do so.
The RSS had said Mr Bhagwat had not compared the Indian Army with Sangh volunteers and his remarks on the matter were "misrepresented".