Complex sentence: Alexander spent most of 1145 and 1146 at the papal court in Rome, but some time in 1145 or 1146 he was one of the witnesses to the peace accord signed between the earls of Chester and Leicester.
Split into simpler sentences: Alexander spent most of 1145 and 1146 in Rome at the papal court. However, sometime in 1145 or 1146, Alexander was one of the witnesses to the peace accord signed between the earls of Chester and Leicester.