A brief discussion of the mutability of History
Much as it troubles me to say it, History is NOT a fixed series of events that happened exactly as recorded. It is quite often that 'History' as described in a particular textbook varies greatly from the actual event when it occurred. This is because history, as recorded for posterity, is subject to the whims of the writer, who was often ordered to embellish, leave out unflattering events, or (in some cases) make up out of whole cloth the descriptive narrative by those in power. And those in power were often the winners of a particular skirmish, battle, or war, or the ruling personage at the time of the event's occurrence. "Winners write the history" is a truism 99.99% of the time.
So why study what is most likely a string of lies? Because doing so allows us to avoid repeating the mistakes our forefathers made. There is no greater truism than "Those who fail to study history are doomed to repeat it, and those who fail to learn from history are simply doomed." Case in point from very recently -- the 400th anniversary of Christopher Columbus' "discovery" of America in 1492 was celebrated by the Great Columbian Exposition in Chicago. Participants by the millions came from all over the world to view exhibits, and enjoy the celebratory spectacle of such a momentous occasion. A mere hundred years later, the event was largely ignored, for the idea of Christopher Columbus as a heroic figure had fallen into disfavour -- after all, there was the physical proof that the Vikings had landed in the new world long before, and the (apocryphal) legend that Madoc of Wales had traded with the natives in the Ohio Valley region as early as the 8th century AD. New excavations have given rise to the possibility of the ancient Egyptians influencing life in Mesoamerica before the time of the Roman Empire.
My suggestion, if you really want to know the truth, is to read descriptive accounts written by historians from both the winning and the losing side, if available -- then combine the two, along with a very large grain of salt, for an approximation of the truth.