The convoy sailed from Southend-on-Sea in the Thames Estuary on 3 July 1940 via the English Channel, where local traffic dispersed to south coast ports.

No support was forthcoming from RAF Fighter Command and in the aftermath, the Prime Minister, Winston Churchill, was critical of the lack of protection afforded to the convoy.

Attacks on minesweepers, escort vessels and anti-invasion patrols rapidly increased and was made worse by a lack of light anti-aircraft guns and the concentration of the air defence effort in the south-east of England, against a possible invasion.

While demanding close escort, the Admiralty required ships to engage unidentified aircraft within 1,500 yd (1,400 m), a practice the RAF considered irresponsible.

More training in aircraft recognition and pilots not flying towards to ships on tracks similar to bombing runs were obvious remedies and with experience, navy gunners made fewer mistakes.

OA convoys incorporated coasters from the Thames to Southampton, Poole, Plymouth, Fowey and Falmouth along the south coast.

The captain of Hartlepool, W. J. Rogerson, saw the Isle of Wight in the distance and With that I went out of the Chart Room door and without the need for binoculars I saw the whole of Cap la Hague, the French coast and also the Channel Islands.

The pilot had also set the altimeter to the local altitude above mean sea level and a siren blared to warn him to bomb and begin to pull out of the dive.

[4] As gunners were running along the decks of Foylebank to reach their action stations, many where hit by bullets or caught by bomb blasts.

An officer ordered him forward as the ship was going to be abandoned and he jumped 10 ft (3.0 m), damaging his back, although he was unaware of this for several hours.

[7] The tug Silverdial was also sunk and the steamers City of Melbourne, East Wales and MV William Wilberforce were damaged by bombs in Portland Harbour.

The chief officer of Deucalion wrote later that the sky seemed full of aircraft which hit the ship with nine bombs and began to sink.

[12][11] Near midnight, the E-Boat S 19 torpedoed Elmcrest 13 nmi (24 km; 15 mi) south of Portland which took on a list as the crew abandoned ship.

Hartlepool was torpedoed by S 26 and abandoned,16 nmi (30 km; 18 mi) south, south-west of Portland, apparently in a sinking condition, the survivors being rescued by destroyer HMS Scimitar; the ship was later beached at Weymouth.

[2] In 2013, the historian Andy Saunders wrote that the convoy was too far from the English coast for fighters easily to have protected it and when the Stukas attacked.

Saunders called the losses inflicted on OA 178 a British failure, which showed the Germans that the Royal Navy and the RAF were incapable of protecting Channel convoys.

After OA 178 local CE and CW coal convoys proved equally vulnerable to the combination of Stukas and S-boote.

The British prime minister, Winston Churchill, issued an Action this Day memo to the Admiralty inquiring about the measures to defend convoys along the south coast, particularly the matter of air cover.