Complex sentence: After Swietopelk tried to carry out foreign policy without approval of the Polish ruler in 1112, Krzywousty invaded his lands and after a three month siege of Nakło, he forced Swietopelk to submit.
Split into simpler sentences: After Swietopelk tried to carry out foreign policy without approval of the Polish ruler in 1112, Krzywousty invaded his lands. After a three month siege of Nakło, he forced Swietopelk to submit.