Complex sentence: In 1551, Ivan Vyrodkov was in charge of the construction of Sviyazhsk-a wooden fortress near Kazan that he would build in 28 days and which would be used as a strong point for capturing the city by the Muscovite army.
Split into simpler sentences: In 1551, Ivan Vyrodkov was in charge of the construction of Sviyazhsk-a wooden fortress near Kazan that he would build in 28 days. This would serve as a strong point for the capture of the city by the Muscovite army.