..
Without the Russians, i.e. Soviets, the U.S. could not have
won the war in Europe. Ask any World War II military expert.


Why -- are these "experts" infallible when it comes to *speculating* what
might have been?



Thus, Germany would have been left with a virtually invincible empire


Somebody stopped, to insert the word "virtually," above. Interesting, no?
:-)



The United States would have concentrated on defense of
the Western Hemisphere and Pacific.


I think somebody is overestimating the U.S. here.
Since when did the U.S. ever concentrate solely on *defense*, and leave other
countries alone? The development of the Bomb embues power. And power
corrupts. If we had the bomb (and nobody else did), there is no reason why
the U.S. could not have thwomped even a vast German Empire, if the right
politicians got the urge.
Obviously, if the Germans had conquered all of Europe, they would have had no
qualms about taking over the seas next, sinking U.S. ships via submarine
attacks whenever they deemed it necessary or expedient. Hence, the U.S. would
need no further pretext to drop the Bomb. A-Bomb here, A-Bomb there, here
A-Bomb, there A-Bomb, everywhere A-Bomb-bomb. Old MacDonald had a farm.
E-i-e-i-oooh.



Without the Bomb, it's a horse of a different color. That would be like
trying to win WWII without the Russians.... :-)






"Never bite-off more than you can chew."

--- Hitler


"Let sleeping dogs lie."

--- the fellow who unwisely woke-up Fischer.






One hundred aircraft carriers by 1945.

That would have been irrelevant to conquering Germany on land.


In fact, whenever the U.S. is about to launch (yet another) land invasion,
this is always preceeded by sending in the aircraft carriers, from which planes
are launched. These planes "pave the way" by pummelling the enemy ground
forces to smithereens. We also always try to establish nearby land airbases
from which to launch air attacks.
It is silly to imply that ground troops are not actually transported by the
aircraft carriers, for they always accompany the transport ships; but then, a
large-scale ground invasion is not necessarily the only way to fight a war.
In fact, heavy losses which were projected for an land invasion of Japan were
used to "justify" the dropping of the Bombs on Hiroshima and Nagasaki. This is
often referred to as evidence of racism, for "we" dropped the Bomb on "the
yellow man," but not on our fellow "white man." But maybe we just ran out of
Bombs.... :-)