The 'Action of 6 June 1942' was a naval action fought between German and US forces as the German raider Stier encountered and sank the US tanker Stanvac Calcutta while cruising in the South Atlantic Ocean off Brazil (6 June 1942).

Stanvac Calcutta was a 10,170-ton tanker with a crew of 42 merchant mariners and an armed guard of nine men. The ship was commanded by Captain Gustav O. Karlsson and the guard detachment by Ensign Edward L. Anderson. Throughout World War II merchant ships were lightly armed, and out of the six US vessels of this type attacked by German raiders, only Stanvac Calcutta and Stephen Hopkins offered serious resistance, and both were sunk. When Anderson was assigned to the ship he was responsible for finding armaments, which proved to be a difficult task, but Anderson managed to acquire one 4-in (101.6-mm) of World War I vintage and one 5-in (127-mm) anti-aircraft gun from the same era. Commanded by Kapitän Horst Gerlach, the 4,778-ton Stier was considerably more heavily armed with six 150-mm (5.91-in) guns, one 37-mm gun, two 20-mm cannon and two 533-mm (21-in) torpedo tubes. Stier was also known to the Germans as Schiff 23 and HSK-6, and to the Allies as Raider 'J'.

Stanvac Calcutta departed Montevideo in Uruguay on 29 May 1942 headed to the north along the coast toward Caripito in Venezuela. One week after leaving Montevideo, at 10.12 on 6 June the US ship was 500 miles (805 km) to the east of Pernambuco in Brazil. The weather was overcast and the sea rough. Suddenly gunfire was heard and the Americans caught sight of Stier emerging from a squall and quickly heading toward Stanvac Calcutta almost head on and signaling the Americans to cut their engines. The Germans apparently believed the tanker was an unarmed merchantman, but before this moment Karlsson and Anderson had planned a course of action for defending the vessel. As soon as the Germans were spotted, Stanvac Calcutta beam-on to the raider and thereby bring her guns to bear, and when the raider closed to an estimated 3,500 yards (3200 m), Anderson ordered his gunners to open fire. The armed guards fired five shots with the aft 4-in (101.6-in) gun and several rounds with the bow anti-aircraft gun. The last of the five shells struck and disabled one of Stier's 150-mm (5.91-in) guns just before the raider began delivering broadsides from her four guns and machine guns.

The US merchant seamen had been trained and were used to man the anti-aircraft gun, which fired continually throughout the battle though it misfired a few times as a result of its ammunition’s age. In 15 minutes of fighting, Stanvac Calcutta was struck several times in the bridge and elsewhere, killing Karlsson and a few other men. After hitting Stier, the guards manning the 4-in (101.6-mm) gun were reported to have been encouraged and continued firing accurately until shell fragments damaged their weapon. The sights were destroyed but the Americans continued shooting until their supply of ready-use ammunition had been exhausted. At this time Anderson ordered two men to bring more ammunition from below deck, though as soon as they left, Gerlach manoeuvred Stier for a torpedo attack. When lined up, Stier fired one torpedo, which headed straight for Stanvac Calcutta and detonated on the port side. Water began flowing into Stanvac Calcutta[]e]'s hull, and the vessel started to list. Several men had been killed in the torpedo’s detonation, and when it was clear that the US ship could not be saved, Anderson ordered the survivors to lower life rafts and abandon ship.