The Battle of Britain Five Months That Changed History, May—October 1940 by James Holland (z-lib.org).epub

Scharnhorst, and the giant battleships Bismarck and Tirpitz. On the matter
of submarines, Germany agreed a 45 per cent parity with Britain and
promised to abide by the 1930 London Treaty Submarine Protocol, which
barred unrestricted submarine warfare against merchant shipping. The
agreement was a coup for Hitler. From having had a navy of just 15,000
men, Germany was now allowed to build a considerable force with the
blessing of the world’s largest naval power. It was British appeasement at
its worst.
From Dönitz’s perspective, however, the agreement showed that the
Kriegsmarine’s future lay in surface vessels, so for an ambitious 48-yearold,
his new command seemed something of a dead-end. However, he had
been a U-boat commander in the last war and, having thrown himself into
his new job, became convinced that not only would Germany one day be at
war with Britain, but that when such a time came to pass, submarines, not
capital ships, would be the key to German naval success. In his view, U-
boats had come very close to winning the war for them in 1914–18, and had
they built more of them rather than battleships, the end result could have
been very different. Submarines had come a long way since then. They
were tougher and faster, could dive quicker – the Mk VII could dive in
about thirty seconds – and had larger, more numerous torpedoes, warheads
that were battery-powered and wakeless, thus making them harder to detect,
and with ranges of up to three miles. Radio technology had also improved.
The new U-boats were equipped with highly effective long- and short-wave
transmitters and receivers. This meant that U-boats could not only
communicate with their base but also with one another. Now, Dönitz
realized, U-boats could operate together, and hunt for enemy shipping as a
pack – a wolfpack as he called it. And while it was true that more advanced
anti-shipping weapons, such as sonar, had been developed, Dönitz believed
they were overrated – a threat, yes, but not a considerable one.
He made little headway in persuading Admiral Raeder, commander of
the Kriegsmarine, the OKM, or the OKM staff, that U-boats were the way
forward, however. Not only were they already committed to the existing
building programme, they did not want to risk, at this stage, breaking the
Anglo-German agreement. Furthermore, unlike Dönitz, they believed that
modern technology and improvements in aircraft range and power put
submarines at a severe disadvantage.