Hundreds of ex-servicemen held a black-flag protest over the delay in implementing one rank, one pension (OROP) in Mohali on Saturday as defence minister Manohar Parrikar inaugurated the Mai Bhago Armed Forces Preparatory Institute.The ex-servicemen from Mohali, Chandigarh and Panchkula owing allegiance to different associations gathered at Gurdwara Singh Shaheedan on the airport road at Sohana, carrying black flags and raising slogans against the Narendra Modi government.The protesters were stopped by police that barricaded the road which led to the institute. The demonstration was held 2 km from the institute.