Complex sentence: In 1812 he married the Russian lady, related to the Tsars, Mrs. Zagriatsky, and established himself in his adopted country, even after the overthrow of Napoleon, and the consequent restoration of the Piedmontese dynasty.
Split into simpler sentences: In 1812 he married a Russian lady, related to the Tsars, Mrs. Zagriatsky. He remained in Russia even after the overthrow of Napoleon and the consequent restoration of the Piedmontese dynasty.