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

The assault on the west had been a huge gamble that had paid off, but at
least then his army and air force – his two strongest arms – had been
fighting a Continental war. The Luftwaffe had been designed for precisely
that, supporting the army, the spearhead for the land attack. In Poland,
Norway and in the west it had repeatedly proved its effectiveness in that
task. General Wever had advised having a strategic bomber force, but with
his death the four-engine bomber programme had been put to bed. It had
been given life again with the He 177 project, but now Udet, with the
blessing of Jeschonnek and Göring, had put that on hold. It meant the
Luftwaffe was now contemplating an air assault without the army beneath
them and without the right tools to effectively do the job; the Luftwaffe did
not have a heavy-bomber force, and it had rather fewer aircraft and crews
than it had before the start of the offensive in the west.
Although Hitler was showing little appetite for a cross-Channel
invasion, he had, however, instructed the Kriegsmarine to start making
feasibility preparations for such an operation. This task had been given to
Konteradmiral Kurt Fricke, Chief of the Naval Staff Operations. Fricke’s
first ideas had been put forward at the end of May and on their basis
preliminary work on an invasion had begun – within the navy, at any rate.
As a starting point, Fricke believed that no invasion could be accomplished
until the RAF had been knocked out. He also favoured invading along
either the south coast or the east coast, but not in the heavily defended
narrows of the Channel. First, however, there were a number of tasks for the
Kriegsmarine: minesweeping, minelaying, the assembly of suitable
shipping, action against the Royal Navy, and the organization of protection
for the transport fleet. Strategic surprise – as Admiral Forbes had correctly
pointed out – would be hard to achieve.
A hunt for shipping had already started by scouring the coasts and rivers
of Holland, Belgium and France for anything that might cross the Channel
and even the North Sea. Germany had possessed no landing craft
whatsoever at the beginning of the war, and by 14 June the Kriegsmarine
had managed to get its hands on just forty-five flat-bottomed barges suitable
for landing troops. Ideas were being put forward for ferro-concrete tanks
that could ‘swim’ across the Channel and then crawl off the flat beaches,
and there were designs for super-fast landing barges. A more practical
solution was to start requisitioning Rhine barges and other craft from
Germany’s inland waterways. Meanwhile, detailed studies were also made