Looking further along in 1915: the tonnage sunk per patrol day shows no
correlation with the tactic used - torpedoed without warning or not. An able
commander and his well-trained crew, a good boat, good weather and visibility, and
good luck produced very different numbers.50. The same tendency can be seen for
results obtained in the Mediterranean, where better weather conditions and
visibility, much weaker defence forces, and generally less neutrals simply offered
more favourable sinking possibilities for the submarines. ...
A typical day of the first unrestricted submarine warfare in 1915, with 4
submarines cruising around the British Isles. This was not yet regarded as a deadly
menace in Great Britain. It seemed merely as a domestic German propaganda bluff,
to distract from the inactivity of the battleship fleet. ...
Again, it can be clearly seen in the Mediterranean: there was no correlation in
the sinking results between restricted and unrestricted warfare. ...
Viewing the 26 boats available during March 1916 and the average 7 on patrol
per day then, one can only characterise this statement by one of the leading
German Navy officers as phantasm, as pure wish-thinking. The highest level of
decision-making in Germany was based on ignoring reality.
The relative number of boats on Merchant War Patrol was not very high,
some 25-27% of those available were used in the Atlantic. The Mediterranean
boats, constantly growing in numbers, suffered from insufficient dockyard
capabilities for repairs and maintenance in 1916 and later.
The unrestricted submarine warfare had to be stopped in April, after the
sinking of the SUSSEX under heavy American diplomatic pressure. From now on
it was clear to the German Government that further unrestricted warfare would
mean a total break with America and, very presumably, war with the USA. ...
And for the glory of the High Sea Fleet, Scheer had stopped the submarine
war in the Atlantic for over 5 months, from May to mid October 1916. Had the
submarines available in the North Sea continued restricted merchant warfare from
May to October 1916, then at least another 1 Mio. BRT of ships would have been
sunk.65 This could have been the last straw for Britain in April 1917. A nice present
from Scheer to England. ...
Why resort to unrestricted submarine warfare in 1917, when it didn’t correlate
with a greater rate of sinkings, but chanced a breakout of war with America?
“[...] the deterrent effect on the neutral powers, which was an essential factor of the whole
plan. 69
The German Navy hoped to frighten the European neutrals – Norway,
Sweden, Denmark and the Netherlands – from carrying on further commerce with
Britain by means of a brutal threat of destruction in a declared ‘war zone’ around
the British Isles. This alone would have decreased British imports/exports by 20-
30%. However, Britain more successfully blackmailed the neutrals to continue their
merchant trade by only releasing a neutral ship out for every neutral ship coming in.
And somehow the neutral shipping companies had to earn their revenues and
profits, and the skippers and the sailors their daily lives, even risking it. After some
weeks in February 1917 it was clear, that the German deterrence didn’t work. A
first miscalculation.
And there was never a ‘total’ unrestricted war. The ships of the Belgian Relief
Commission had to be spared in any case. There existed special agreements
between Germany and the European neutrals allowing them a certain amount of
trade with Britain in exchange for trading with German. Hospital ships were
generally spared. Passenger liners, un-armed allied vessels in the Mediterranean, or
certain neutrals like Spain were treated according to the actual diplomatic situation.
Submarine commanders at sea received a confusing stream of orders regarding
their actions.70
But why to break with America by unrestricted submarine warfare, why not
continue with restricted warfare?
Birnbaum called the period of decision-making in Germany between Dec.
1916 and Jan. 1917 [...] a race between peace and unrestricted warfare [...]”71
And this race took place in the highest military and civil circles in Germany.
At the end of 1916, President Wilson tried to mediate peace between the Allies and
Germany. The diplomatic negotiations between Germany and the USA ran all over
December and January 1917. The German Ambassador in Washington, Count
Bernstorff, was quite sure in January 1917, that peace negotiations with Wilson as
mediator could start very soon, within weeks.