[2] He entered the Royal Navy in 1824, and twelve years later gained his first experience of Arctic exploration as mate of HMS Terror on an expedition commanded by Captain George Back.

The ships sailed south on the Atlantic, navigated through the Strait of Magellan to the Pacific Ocean assisted by the steam-sloop HMS Gorgon.

McClure and his crew undertook a sledge journey and were rescued when they happened upon a party from HMS Resolute – one of the ships commanded by Sir Edward Belcher, who sailed into the Arctic region from the east.

Enterprise returned to Point Barrow in 1850, a fortnight later than Investigator, and found the passage blocked by winter ice.

They had to turn back and return the following year; it conducted its own Arctic explorations, but credit for the Northwest Passage already belonged to McClure.

Following an honourable acquittal, McClure was knighted and promoted to post-rank, his commission being dated back four years in recognition of his special services.

[3] From 1856 to 1861 he served in eastern waters, commanding a division of the Naval Brigade before Canton in 1858, for which he received the Order of the Bath.