1. The Battle of Heligoland Bight (August 1914) was the first naval battle of WW1
The British fleet ambushed and sunk three German light cruisers and one destroyer.
2. In 1914 SM U-9 (a German U-boat) sank 3 British armed cruisers in under an hour
3. On 7 May 1915 the cruise ship Lusitania was torpedoed by a German U-boat
1,198 people were killed, including 128 Americans. The wrecklessness of German submarine warfare was an influence on the United States decision to join the Allies in 1917.
4. Between October 1916 and January 1917 1,400,000 tons of Allied shipping was lost to German U-boats
5. Germany built 375 U-boats, 202 of which were lost
Of the 375 German submarines – U-boats – that set sail from German ports in World War One, 202 were lost in action. Most of them were destroyed by the Allies – mechanical failure and accidents accounted for others. The German submarines terrorised Allied shipping, sinking around 2,600 vessels. Yet the sailors sent to serve in U-boats knew their chances of survival were low. Out of 17,000 men who served, more than 5,100 lost their lives. Serving on a U-boat was one of the most dangerous occupations in the entire war.
6. 50% of all British merchant shipping was sunk by German U-boats
37 U Boat commanders sank 2,686 ships with a total of 5,929,772 tons. Lothar von Arnauld de la Perière (1886–1941) was the most successful U-boat commander of World War I and of any submarine commander in history. Between 1915–18, he made 14 patrols in command of U-35, sinking 189 merchant vessels and two gunboats. He transferred to U-139 in May 1918 and sank a further five merchant ships, making 194 ships sunk totalling 453,716 GRT. After serving as an instructor in the Turkish Navy between 1932–38, he returned to the Kriegsmarine and during World War II served as naval commandant for western France with the rank of Vizeadmiral. He was killed in February 1941 when his aircraft crashed on take off at Le Bourget Airport, Paris. https://uboat.net/wwi/men/commanders/most_successful.html
7. The Battle of Jutland (31 May – 1 June 1916) was the largest sea battle of the war
In the largest full-frontal naval battle of the war, 14 British ships were lost to Germany’s 11. Britain also lost more than twice as many sailors than Germany. However, it was not the knock-out blow that the Germans required.
8. The North Sea was heavily mined by both sides
Under a 1907 treaty, opponents could only mine 3 miles off an enemy’s coastline, but both sides ignored this rule.
9. The success of German U-boat attacks caused the disastrous Passchendaele offensive
A main reason why the Passchendale campaign was launched was to capture the German U-boats based at Flanders. The attack failed however, with Britain suffering massive casualties.
10. The Allied naval blockade of Germany (August 1914 – January 1919) was devastatingly effective
Germany was heavily reliant on imports. An academic study in 1928 put the death toll caused by the blockade at 424,000 German lives.