Who said without troops ?
Take 200,000 in the Grand Armee and leave them fighting in Britain - who (and how many) faces off against Austria and Russia (and probably Prussia too)
If Napoleon is able to land 200,000 troops in England, that means he can cross the English Channel at will.
If he takes London its going to bring the politicians to the table. There will be die-hards saying to fight on and wear the French down, but when faced with the reality of what this would mean, most politicians would deal.
This isn't Russia. The King can't say "Burn London" and withdraw.f
Take 200,000 in the Grand Armee and leave them fighting in Britain - who (and how many) faces off against Austria and Russia (and probably Prussia too)
At that time, Prussia's neutrality had been bought. The price was Hanover. What caused Prussia to go to war in 1806 was the settlement that Napoleon imposed in Germany after defeating Austria and Russia at Austerlitz.
And I say it again. France and its allies had ample reserves if needed. You could have Napoleon on one front and another marshall on another front.
Plus there are possibilities that, without Cadiz and Trafalgar, Napoleon Lansing in Britain in summer. And so if the british defeat seems certain, the coalition may well vanish, prefering to accept letting France and Britain settle alone their century-long conflict.
Do you think winning wars and battle is a mere issue of number of troops ?
From 1796 to 1806, Napoleon always had a numerical disadvantage in its campaigns and battles. This did not prevent him, nor Davout (who won the battle of Auerstedt against a prussian army that numbered 3 times as many soldiers as his own army), nor other french marshall from winning the battles.
Do you know how many troops there were in the austrian and russian armies that fought at Austerlitz ? 85,000 ...
Such armies with 85,000 troops or 150,000 troops could do everything but invading napoleonic France.
I could very well tease you too with your british accent and say to you it's not because you don't want Britain to lose that Britain is undefeatable in this alternate history.
The russians and the austrians did not enter this war in order to protect Britain.
The austrians did because they did not accept the settlement Napoleon had imposed in Germany in 1803.
The russians did for their own reasons, among which Napoleon was conflicting them in the Mediterranean and in Italy. But the general case was not protecting Britain : it was about franco-russian conflict and the personal opinion of Russia's new czar (Alexandre I).
If Britain is invaded by such a big army, it is beheaded and that's all. So it takes its loss and accepts a settlement. The same way as Athens finally lost the peloponesian war.
In the peninsula war, it was guerilla warfare. And the french only began losing in the last part of 1812 and 1813 in close link with the disastrous napoleonic campaign in Russia.
What happened in Russia ? Napoleon gave up a good strategy and changed it for a disastrous and absurd one (in fact it was not even a strategy) : going as deep as possible into Russia in order to have a pitched battle with the russian army that was retreating before him.
The Grand Army, or call it the Army for England, was not all the troops napoleonic France and its allies had.
Napoleon's invasion mirrors Sealion. Any force that manages to slip by the RN/RAF will be too small to have a major effect on the invader's total strength and strategic position. Any force large enough to seriously threaten the UK means that the RN/RAF has been removed from the equation, and thus the strategic picture has been altered significantly. That needs to be taken into account in any post-landing speculation.