make op. jubilee work, what would be the response of the germans? would it become a fully fleged invasion after there was surprising succes?
This would probably be a total disaster!
One reason that Dieppe happened was to show the US that 'land a bunch of guys on the beach and seize a harbour' wouldn't work.
If Dieppe 'succeeded', then the US would absolutely insist that the invasion of France happen in '43, without all the work that made Overlord successful.
While it's true that German defenses were weaker in '43 than in '44, the Allies were weaker yet.
I'm not saying that an Normandy invasion in '43 would necessarily fail. It would, however have a strong chance of failing, ESPECIALLY if Dieppe 'proved' that all the logistical innovations (massive numbers of landing craft, Mulberry harbours, PLUTO, hedge cutting tanks, etc., etc.) are necessary.
Even if the WAllies do get a foothold, the fight will be long and bloody and any advance would be MUCH slower than OTL.
A failure could mean the WAllies try elsewhere - like an invasion up through Greece. Which would mean the Soviets own most of Germany - and probably half of France.
My two cents worth.