Complex sentence: In April 1312, Edward made Gaveston the governor of Scarborough Castle, but his tenure would be brief; in May, the Earls of Pembroke and Warenne, together with Henry de Percy, besieged and took the castle.
Split into simpler sentences: In April 1312, Edward made Gaveston the governor of Scarborough Castle, but his tenure would be brief. In May, the Earls of Pembroke and Warenne, together with Henry de Percy, besieged and took the castle.