Beginning near the northern Orkneys, the barrier ran to Udsire Light, near Bergen, on the coast of Norway, 230 miles. Its average width was 25 miles, in some places it was 35 miles across, and at no point was it less than 15 miles wide. At its narrowest, this meant more than an hour's run for a submarine. Mines were planted, row after row, at various depths. If a U-boat proceeded on or near the surface, it would encounter from six to ten lines of mines. If it tried to break through by going deeper, there were more of the deadly explosives. Submergence was, in fact, as dangerous as running the gauntlet on the surface. No matter how far the sub went down there were mines to meet it, to the furthest limit of submarine descent. One touch--even a slight jar from the vibration of the U-boat--was enough to set off one of these mines, and when it exploded the U-boat was done for. Mine-laying was not the only role played by the American force, Captain Belknap wrote: In addition to the value of the barrage itself, in keeping the enemy submarines in or from their bases, the mine squadrons were expected to serve as bait, to draw out the German fleet; the squadrons' role being neatly expressed by one high officer as "an important military offensive with a front seat at the Second Battle of Jutland." This ever present possibility and the fact that the working ground lay in the principal thoroughfare of enemy submarines, with attendant incidents of periscope sightings, submarine reports, depth charges, smoke screens, floating mines, and dead Germans floating by, lent spice to the work, which, like the proverbial sporting life, was often hard but never dull. * * * On every excursion, during the mine laying, one or more of the mines would go off fairly close astern--lest we forget! The mines were very sensitive, and no witness of an excursion could retain any doubt as to the fate of a submarine that "luckless dares our silent wake." The eastern end of the barrage extended to the territorial waters of Norway. That country being neutral we could not, of course, mine to its shores. With the growth of the barrier, U-boats took advantage of this, going within the three-mile limit to slip by into the open sea. The Norwegian Government then announced its decision to mine its waters, which closed that gap. Our original plan was to plant mines clear to the Orkneys, and this we urged. But Admiral Beatty and others strongly objected, fearing that it might hamper the operations of the Grand Fleet. So the mine-fields ended ten miles east of the islands. But this ten-mile passage was heavily patroled, and any "sub" attempting to pass that way must run the risk of attack by numerous naval vessels. Thus the U-boats could not get through anywhere except at great risk. Months were required to lay that barrier, and during that time there were unmined areas through which vessels could pass.