Almost immediately, Swan prepared to sail to Scotland, to participate in clearing the huge North Sea Mine Barrage laid in 1918 to prevent warships and submarines of German High Seas Fleet from breaking out into the Atlantic.
Their task was monumental, as the American minesweepers (in company with modified sub chasers and British minesweepers) were tasked with sweeping over 70,000 mines laid in an area roughly 240mi long by 25mi wide, or over 6000sqmi.