I bought a copy of Common Errors in History, which someone mentioned recently on LW.  There were no copies on Amazon or other bookselling sites, but I found a copy on Ebay.  No wonder it was hard to get - it's a 24-page pamphlet that was printed once, in 1945, by "The Historical Association," London.

I tried to find some common failures of rationality underlying the "common errors" listed.  This is what I concluded:

English students in the mid-20th century learned a lot of history.

This booklet is full of statements such as, "The facts relating to the Corn Laws [of 1815-1849] are more often than not mis-stated in school examination papers," and, "The blockade of Brest and Toulon [during the Napoleonic wars] is usually misunderstood."  My history lessons consisted primarily of repeatedly learning about the American Revolution and making turkeys or pilgrim hats out of colored cardboard.

The English sincerely apologize for their history.

In other countries, textbook authors try to make their own countries look good.  In England, that would seem gauche.  The entries on "Religion in the New England Colonies", "The Causes of the American War of Independence", "The First Chinese War, 1839-42",  "Gladstone and the Turks", and "The Manchurian Crisis, 1931-32" complain that British textbook accounts place all of the blame on Britain.

History is simplified in order to assign blame and credit.

In numerous of the 20 entries, notably "The Dissolution of the Monasteries and Education", "Religion in the New England Colonies", "The Enclosure Movement", "The Causes of the American War of Independence", "The Great Trek", "The First Chinese War", "The Elementary Education Act", and "The Manchurian Crisis", the tract alleges that standard accounts are simplified; and they appear to be simplified in ways that allow a simple causal summary, preferably with one person, side, or act of legislation to receive credit or blame.

Not always.  "The Great Trek" says that the Boers' depart is usually explained as due to their [blameworthy] indignation that the British had freed their slaves; whereas in fact they had a variety of different, equally blameworthy, reasons for leaving.  And the entry on "Bismarck's Alliances" says that the textbook account is overly-complex in that it introduces a second treaty that did not exist.

This is the only general principle I could extract from the book, so it may just be a statistical accident.

If anyone would like a copy of the book, send me an email at gmail. But it's very boring.