HMS Conqueror fired three Mark 8 torpedoes at the Belgrano. The design of the Mark 8 dated back to 1925. Two torpedoes hit at an estimated contact speed of 41knots. The first blew off the Belgrano's bow and the second hit aft of the side armour and punched a hole into a rear machine room where it exploded. Despite the bulkheads holding, the loss of electrical power and the inrush of water through the entrance hole of the second torpedo, caused the Belgrano to take on water and settle by the bow. The Captain ordered the crew to abandon ship 20 minutes after the second hit.
One of the two Argentine destoyer escorts to the Belgrano, the AGA Bouchard (D26) was apparently hit by the third Mark 8 torpedo which failed to detonate but left an impact mark.

HMS Conqueror also carried the Mark 24 acoustic torpedo known as Tigerfish but this was deemed to be unreliable so the older and proven Mark 8 was fired.