There really is no plausible reason to have that many German troops around Helsinki besides an imminent invasion.
IOTL Germany moved its entire army up to the border & deployed into what could only be offensive positions, but Stalin's big worry was not to piss 'em off. He was absolutely convinced that Hitler would never invade, wouldn't believe it even when it happened, & went into depression for over a week when it was proven to him.
Furthermore, IOTL Germany has 1 div. in Finland as early as Oct. 1940. When Molotov was in Berlin in Nov. negotiating for the USSR to join the Axis he demanded an explanation, & Stalin made their withdrawal one of his conditions. Everyone knew those German troops were there to guarantee Finland's borders
The approaches to Tallinn and the Gulf of Riga would be mined by the Soviets and significant Soviet naval forces would be operating in those areas.
IOTL the approaches to Tallinn & Riga were never mined, except by the Germans. The USSR was caught entirely off-guard, was unable for months to take the initiative, & the offensive proceeded so fast that by the time the Soviets thought of doing it, it was too late.
As for Soviet naval forces, IOTL they were penned in Kronstadt, Leningrad, & Tallinn by minefields that were laid by German minelayers that had been concealed in Helsinki. Something like a quarter of the Soviet ships were sunk, mostly by German & Finnish mines, in the largest loss of life to a minefield in history. So, other than submarines, the Red Banner Baltic Fleet had no capability to interfere with German-Finnish naval ops in the Baltic. Our convoys will be escorted by a large number of destroyers to protect vs Soviet submarines.
Politically allowing several divisions of German troops in the nation's capital...
After a careful consideration of your criticisms & a more thorough review of Finnish war objectives & their limited willingness to cooperate with Barbarossa, I have
(regretfully) concluded that you are most likely correct, & they would probably
not have allowed the Germans to stage from Helsinki.
We will therefore assemble our ships at Danzig. After the invasion forces move out from Memel
(Klaipeda) & their assembly areas SE. of Memel, we'll move the 1st echelon of ships & sealifted divisions into Memel for departure. It is 236 miles from Memel to Riga, so by using 12-kt. ships our forces can be there in 20 hours. It is 316 miles from Memel to Tallinn, so by using 15-kt. ships our forces can be there in 21 hours.
The most important loss in this revised plan is the 4-hour transit time from Helsinki to Tallinn, but upon reflection that shouldn't be critical because the Soviet Fleet will be completely taken by surprise anyway & is unlikely to be able to intervene.
(Of course, the Germans wouldn't know that in advance, which is why they would have preferred to use Helsinki.)
My apologies to Catspoke if my defense of my earlier position sounded a little too insistent. Your criticisms also contributed to this re-evaluation.
...and AdA, your point about the patronizing tone is well-taken. Initially I had him speak with much greater reserve, but my own frustration with the limitations of the
Barbarossa plan kept coming thru. Finally I decided to give up & just let him say what he wanted & let the chips fall where they may. On occasions when I've felt very strongly about something, following weeks of trying to get my point across in staff conferences, I've gotten carried away with myself in a similar fashion in front of general officers. Both times this happened I expected to get slapped down pretty hard, but I didn't. One general even said afterward that it was refreshing to hear a "spirited" presentation instead of the dry, monotone briefings they get exposed to all the time.
Go figure.
As for the Lettow-Vorbeck thing, you're right. He wasn't popular in Nazi circles, but he was a lot more popular among the General Staff than Hitler was. He was the only bona fide military hero from WW1.
Thegn.