'MAG1' was a British naval undertaking in which the minesweepers Boston, Cromarty and Cromer of the 14^th Minesweeping Flotilla, together with a number of danlayers and anti-submarine vessels, swept an Axis minefield off Mersa Matruh on the north coast of Egypt (9 November 1942).

The undertaking, which cleared 46 mines and marked the new channel into the port, helped to open this port to support the 'Guillotine' (ii) advance of Lieutenant General B. L. Montgomery’s 8^th Army after its victory over Generalfeldmarschall Erwin Rommel’s Deutsch-Italienische Panzerarmee in the 'Lightfoot' and 'Supercharge' (ii) phases of the 2^nd Battle of El Alamein.