Complex sentence: He acted as second-in-command to Ludwig von Hagemeister, a Baltic German, and the men were assigned to serve the Russian-American Company in New Archangel, reaching the settlement in late 1817, in present-day Alaska.
Split into simpler sentences: He acted as second-in-command to Ludwig von Hagemeister, a Baltic German. Hagemeister and Yanovsky reached the settlement in late 1817, in present-day Alaska.