George,

if you read my post carefully you will see that we agree on the potential helpfulness of a work based on secondary sources. I never wrote or implied that using (only) secondary sources is "wrong", also because one has to do that, if only to disagree with and amend earlier works. Basing one's work exclusively on primary sources would not be scholarly sound (except in the case where secondary sources do not exist). The important thing is not to claim to have written a "new" history of Waterloo when every single fact in your book comes from other scholars. Even more important is not to pretend that you spent time perusing primary sources when all what you did was using what your colleagues found.

As for the problem of coping with unknown foreign languages and the second instance you mentioned, I think it has to do a lot with professional competence, intellectual honesty and common sense. In other words, why should I write a history of Waterloo when the only language I can read is English ? The only reason I can think of is that I want to make some money at the expense of readers that have (or think they have) an interest for history but know nothing about it and cannot judge properly my work. Probably this is not terrible (both the readers and I get what we want), but in my opinion this is not what a scholar in the fullest sense of the word should do. The military history of the English-speaking world offers plenty of battles fought by two English-speaking sides, and there is no need to do a disservice to the readers and waste paper.

Best,

Giorgio