How long was Napoleon in the Ecole Militaire?

I suppose the longest range accomplishment of Napoleon was his arrival in the Russian city of Moscow in 1812, only to find they had all gone & left for St Petersburg, and Moscow was in flames....

He ruled from March 20th 1804, to June 22nd 1815 and then another 100 days. never

For 9 years 328 day prior to his exile at Elba and an additional 94 days after his escape from Elba.

He was the First Consul of France from 12 December 1799 until 18 May 1804.

About 10 years.