NEW DELHI: The sinking of PNS Ghazi during the Indo-Pak war of 1971 has long been an unsolved mystery. With Karan Johar sharing the first poster of his movie, The Ghazi attack (India’s first war-at-sea film that is based on the mysterious sinking of PNS Ghazi) the other day, the debate on what caused the blast on board the Pakistani vessel has been renewed, reports foreign media.

On December 5, 1971, a few local fishermen visited India’s Eastern Naval Command with pieces of wreckage and reported the presence of a large oil slick in the area. As a result of the investigation, it turned out to be a sunken the over 300-foot long submarine — The Ghazi. Formerly USS Diablo, PNS Ghazi had been built during World War II. Leased out to Pakistan, it had been renamed Ghazi.

South Asia’s first submarine, PNS Ghazi was Pakistan’s only submarine with a capacity to travel over 11000 nautical miles to reach Bay of Bengal and undertake operations on India’s eastern coast. How it met destruction, there are differing accounts. It is claimed by Indian navy that Ghazi was lured into a trap  by Vice-Admiral Krishnan, the Commanding Flag Officer of the Eastern Naval Command, by letting Ghazi believe that INS Vikrant, the Indian aircraft carrier, was in the area near Vizag, by sailing out INS Rajput, an ageing WWII destroyer already due in Vishakapatnam for decommissioning. INS Rajput pretended to be INS Vikrant, sailed out of the Vizag harbour and generated heavy wireless traffic, leading the PNS Ghazi to believe that it had received the right intel about the aircraft carrier.

As he hoped, PNS Ghazi prowled perilously close to the Indian coast, searching for its elusive quarry.

On the night of December 3-4, 1971, an explosion tore through the PNS Ghazi, blowing open its bow, crumpling the hull and cracking open the water-tight compartments. Seawater rushed in, drowning the crew as the submarine crashed to the seabed. On December 6, three days after the sinking of the PNS Ghazi, INS launched its first airstrike.

So, what exactly caused the blast on PNS Ghazi? This is where the debate arises. Indian Navy claims the submarine was destroyed by depth charges fired by its ship INS Rajput. Pakistani authorities say the submarine sank because of either an internal explosion or accidental blast of mines that the submarine itself was laying around Vizag harbour.

According to the Indian Navy:

At 00:14 on 4 December 1971, INS Rajput’s sonar room reported what sounded like a submarine changing depth, about half mile ahead. Captain Inder Singh ordered a sharp turn and immediately fired two depth charges from the the ship’s Mk.IV DCTs. Less than a minute later, at 00:15, a massive underwater explosion shook the destroyer. The crewmen of INS Rajput were unsure what had happened; some sailors briefly thought their destroyer had been torpedoed due to the force of the explosion. Lookouts on INS Rajput saw what was possibly an oil slick in the area. Singh felt certain he had sunk a Pakistani submarine and relayed this to Vice Admiral Krishnan at Vizag. Several minutes later, Vice Admiral Krishnan was informed that a beach patrolman in Vizag had also heard a huge explosion at 00:15.

INS Rajput then departed the area and proceed to join up with the INS Vikrant battle group. After sunrise, local fishermen saw an oil slick and some floating debris in the area. Included in the debris was an unused submariner life vest labelled “USS DIABLO”.

According to the Pakistani Navy:

PNS Ghazi commenced laying a small minefield east of the Vishakapatnam harbor mouth on the overnight of 2-3 December 1971. Then at daybreak on 3 December, it headed out to deeper water to search for the INS Vikrant battle group. Not finding it, PNS Ghazi returned to the Vishakapatnam harbor mouth area at sunset to resume laying the minefield. As the lights ashore were blacked out, PNS Ghazi may have misjudged her position and doubled back into her own minefield around midnight; about 10-15 minutes before the INS Rajput depth charging. Thus, it was the accidental detonation of its own mines that destroyed the Ghazi and not INS Rajput‘s depth charges.

Over the years, the mystery surrounding the sinking of PNS Ghazi has endured. Today, the submarine lies embedded in the Vizag seabed about 1.5 nautical miles from the breakwaters. Close to the harbour channel, the spot has been marked on navigational maps to help ships avoid the wreck.

Vice Admiral (retd) G M Hiranandani (whose book, Transition to Triumph, gives a detailed history of the Indian Navy) says, “The truth about the Ghazi, which remains on what the submarine community calls the ‘eternal parole’, lies somewhere between the Indian and Pakistani versions of the sinking but no one knows exactly where.”