The Haryana unit of the Bharatiya Janata Party (BJP) and the party's ex-servicemen's cell is organising the rally.
BJP spokesperson Capt Abhimanyu Sunday said Gen V.K. Singh will speak as "a distinguished guest".
V.K. Singh had last week termed as "very speculative" reports that he was joining a political party.
Abhimanyu said the organising committee met here and reviewed preparations. It discussed issues of national security and welfare of ex-servicemen, to be raised by Modi during the rally.
Modi is the chief of BJP's campaign committee for the 2014 Lok Sabha elections and seen to be its prime ministerial candidate.
Abhimanyu said: "This will be the largest rally on issues of national security and welfare of ex-servicemen. Over 1.5 lakh people will attend."
He said several retired officers from the three services and paramilitary forces along with gallantry award winners and families of martyrs would attend the rally.
He said Pakistan continues to abet cross-border terrorism and there was an increase in incursions by China.
"The infirm and inconsistent defence and foreign policies of the UPA (United Progressive Alliance) government have caused grave threat to national security. There is need for a leadership that can enthuse the forces," he added.
--IANS (Posted on 08-09-2013)