The British admiralty decided in April, 1915, to use some other means besides the employment of torpedo boats and destroyers to keep watch for German submarines, and innocent-looking fishing trawlers were used for the purpose. While these could give no fight against a submarine, it was intended that they would carefully make for land to report after sighting one of the hostile craft. The Germans, discovering this strategy, then began to sink trawlers when they found them. On the morning of April 5, 1915, one of these small craft was sighted and chased by the U-20. After a pursuit of an hour or more the German ship was near enough for members of her crew to fire on the trawler with rifles. Her crew got into the small boat and were picked up later by a steamer. The trawler was sent to the bottom.
The U-20 still kept up her raiding. On the 5th of April, 1915, she overtook the steamer Northland, a 2,000-ton ship, and torpedoed her off Beachy Head. The crew of the steamer were able to escape, although their ship went down only ten minutes after the submarine caught up with it.
The use of nets to catch submarines was vindicated, when on the 6th of April, 1915, one of these vessels became entangled in a steel net near Dover and was held fast. The loss of the U-29, which was commanded by the famous Otto von Weddigen, who commanded the U-9 when she sank the Hogue, Cressy, and Aboukir in September, 1914, was confirmed by a report issued by the German admiralty on April 7, 1915, after rumors of her loss had circulated throughout England and France for a number of weeks.
In order to encourage resistance on the part of crews of British vessels attacked by German submarines, the British Government rewarded the crew of the steamship Vosges. It was announced on April 9, 1915, that the captain had been given a commission as a lieutenant in the Royal Naval Reserve and the Distinguished Service Cross; the remaining officers were given gold watches, and the crew were given $15 per man.
Rumors had reached the outside world that the German submarines were using hidden spots to store fuel and provisions so that they might go about their raiding without having to return to German ports for reprovisioning. Neutral nations, such as the Netherlands and Norway, found it necessary, to maintain their neutrality, to keep watch for such action. On the 9th of April, 1915, Norwegian airmen reported to their Government that such a cache had been discovered by them behind the cliffs in Bergen Bay. Submarines found there were ordered to intern or to leave immediately, and chose to do the latter.
Certain acts of the commanders of German submarines seemed to make it evident that their intention was to sink ships of every description, no matter where found, in order to make the "war zone" a reality, and to make it shunned by neutral as well as belligerent ships. Thus the Dutch steamship Katwyk, which lay at anchor seven miles west of the North Hinder Lightship off the Dutch coast, was sunk. This lightship was maintained by the Netherlands Government and stood at the mouth of the River Scheldt, forty-five miles northwest of Flushing. The Katwyk was stationary there on the night of April 14, 1915, when the crew felt a great shock and saw that their ship was rapidly taking water. They managed to reach the lightship in their lifeboats just as their vessel sank. The same submarine sank the British steamer Ptarmigan only a few hours later.
Among victims flying the flags of neutral nations the next ship was of American register. This was the tank steamship Gulflight, which was torpedoed off the Scilly Islands on the 29th of May, 1915. The hole made in her hull was not large enough to cause her to sink, and she was able to get to port. But during the excitement of the attack her captain died of heart failure and two of her crew jumped into the sea and were drowned. Three days later the French steamship Europe and the British ship Fulgent were sent to the bottom, probably by the same submarine.
The month of May, 1915, had opened with greater activity on the part of German submarines than had been shown for many weeks previous. Between the 1st and the 3d of that month seven ships were torpedoed, four of them being British, one Swedish, and two Norwegian. By the 5th of May, 1915, ten British trawlers had been sunk; some of these were armed for attack on either German submarines or torpedo boats.