HX convoys sailed eastwards from Halifax, Nova Scotia in Canada, to Liverpool and other ports in Britain.

[2] HX convoys were revived in 1939 at the beginning of the Battle of the Atlantic and were run until the end, the longest continuous series of the war.

[4] HX convoys were initially considered fast and made up of ships that could make 9–13 kn (17–24 km/h; 10–15 mph), the voyage from New York to Liverpool taking an average of 15.2 days.

A parallel series of slow convoys (SC), was run for ships making 7.7–8 kn (14.3–14.8 km/h; 8.9–9.2 mph), which took about 15.4 days from Sydney, Nova Scotia.

Delays for diversions and bad weather could lead to escort vessels at the ocean rendezvous running low on fuel and having to return.