Yes, and Russia was very fortunate in the fact that the people of the Crimea heavily favoured Russia.
Russia was forced into having to make a choice on Crimea in that it could give up military ground that was essential to Russia, or it could fight for it.
The existing status quo was working for both sides but America decided that wasn't good enough for the agenda going forward.
Could the status quo have been 'good enough' for America's agenda too? Was a war for phony reasons necessary? Do you know the real reasons?
I can't say for sure how much support there is for Russia in the Donbass but we know it's considerable. Maybe somebody can tell us, sans propaganda.
However, it was significant enough to allow a proxy fight on Russia's behalf, as you have acknowledged.