Complex sentence: Griboyedov and other members of his mission, seeing that the situation was bad, prepared for a siege and sealed all the windows and doors, armed and in full uniform, resolved to defend to the last drop of blood.
Split into simpler sentences: Griboyedov and other members of his mission had prepared for a siege and sealed all the windows and doors. Armed and in full uniform, they were resolved to defend to the last drop of blood.