Complex sentence: Before 468, Heraclius was probably the "Comes rei militaris" of the Eastern court; he was sent with troops to support the Lazi against the Sassanids and the Iberians, but his allies failed to adequately supply his troops and Heraclius was forced to withdraw.
Split into simpler sentences: Before 468, Heraclius was probably the "Comes rei militaris" of the Eastern court. He was sent with troops to support the Lazi against the Sassanids and the Iberians, but his allies failed to adequately supply his troops, forcing him to withdraw.