Redirecting the money for Germany's major surface ships into U-boats would give Britain advance warning of the threat. The Royal Navy could respond with large numbers of escorts built under the London Treaty's exemptions for small, slow vessels. Giving up Scharnhorst, Gneisenau and other heavy ships would also remove much of the force needed for an invasion of Norway. British battleships and carriers would then be available for the Mediterranean, potentially making attacks on the Italian fleet much heavier. With Norway still outside German control, British convoys could use routes farther north more predictably even if France fell. The larger submarine force therefore comes with lost German options and a different British response.
Notable Point · 52:47-56:48
How a submarine-first German fleet would change British strategy
More U-boats bought at the expense of German surface ships would warn Britain to build escorts, obstruct the Norway invasion and release British capital ships for the Mediterranean.