In fact history is the story of victors and not the real truth. Most of the time, real heroes are hidden by victors and sometimes betrayers are illuminated as heroes. With the passage of time such bogus heroes considered as true heroes even by the people who belonged to the losing party as well. Such people even consider their nation itself as an object of shame though they are great in many ways.
Quote -"This quote I’ve seen has been attributed to George Orwell, Napoleon Bonaparte, Mark Twain, Walter Benjamin, Niccolo Machiavelli, Winston Churchill and Jawaharlal Nehru" unquote
Schools textbooks are composed through a selection of facts, often reconstructed in a teleological way where the aim is the constitution of national states, in particular one's own, but aware of this one, and in general comprehended the “horizons of interests” that every history book has, we can say that they are quite reliable.
la historia se construye con selecciòn de documentos, por ende no puede reflejar la realidad como en un espejo; por otra parte los equipos d einvestigacion siempre tienen perspectivas. No obstante ello no autoriza a sostener que ella sea un amera ficiòn . Sòlo indagando en las investigaciones històricas, desde un saber inevitablemente situado, podemos comprender aspectos de la sobredterminaciòn de coyunturas del presente.
I suggest that there needs be a distinction between history and history textbooks. For history books one simply has to investigate the author. History textbooks are however an expression of nationalism at the time when the book was written. Britain's colonial and empire history as portrayed in textbooks of the first half of the 20th Century are different from the way it is portrayed today. Similarly, French and German history textbooks 1871-1914 reflect the attitudes of logical victory or burning resentment at defeat. At the extreme end of the scale, totalitarian governments have a total control over history textbooks.
Having in mind that Nations are a recent political construct I would say, most nations have "romanticized" their history. Most nations go through this period called "national romanticism" where they try to find their roots as far back as possible, and as part of that journey, they create narratives and what I would call non-existent history so that they can feel that they are descended from prehistorical hero's or legend. In most cases, this has no basis at all if you could time travel and speak to anyone before the French revolution you would understand that they never understood the notion of nation as we do today. So this historical-political process of creating national history books has been based on the simple premise that we all agree to believe in them as that is what keeps a nation together.