I recently watch a VICE documentary on the rapid growth of heroin use in Iran and one of the reasons they attributed to the cause of this was the techniques used by America in Afghanistan against the Taliban. These techniques didnt work and the effects has spread.
Has there ever been a successful military occupation of another country that delivered democracy to the occupied country?
Your title and self-text do not ask the same thing. Stability and democracy are not equivalent.
Germany post WW2 , specifically West Germany, turned into a stable democracy after the western allies ended their occupation. Same could be said for Japan after their American occupation.
Douglas MacArthur and his administration did an excellent job of stabilizing Japan after the war. In that case though you could argue that the population of Japan were willing to work with him. Also Japan had been a democracy of sorts before the war.
As stated stability doesn't equal democracy. There are countless cases of authoritarian regimes equalling stability etc.
I would point out the American interventions in the Carribean as being stabilizing in the most part. The 1983 Invasion of Grenada quelled a increasingly violent country. The 20 year 1914 occupation of Haiti also led to a mostly stable country. So too was the 1916 Occupation of the Dominican Republic beneficial. They were not all performed in the interest of stabilization, but undeniably it worked.
The purposeful occupation of countries in the name of self-less stabilization is a relatively modern concept, so they do seem to be rare.
The United Nations has obviously had success in partial occupation and monitoring. Not quite fitting for the question, of course.