Churchill wrote:Hi Rob & Tom,
You are both right and I misread the term "Brigadier" you are quite correct the term would have been Brigadier General or Major General at the time of Blenheim.
Eh, sorta. A Brigadier General was not a substantive rank; it was a temporary appointment and existed only as long as a particular colonel or lieutenant colonel was commanding a brigade. For example, both Rowe and Ferguson were still colonels substantively, but they were commanding more than just their own regiment and therefore addressed as Brigadier General by courtesy.
A British Brigadier General (pre 1922) would be addressed as a Brigadier General, but he wasn't really a general, wasn't paid as a general, and would stop being a Brigadier General as soon as he was no longer commanding more than his regiment.
Naturally, it's even weirder in the French Army. At least by the Seven Years War, Brigadier was less a rank and more a certificate that could be held by colonels, lieutenant colonels, or even captains. Whoever had the oldest warrant for a brigadier would command the brigade. However, the warrants were only issued for one arm, and the holder could not command mixed forces. The advantage is that skilled but poor lieutenant colonels could become brigadiers without having to purchase a regiment, which was rather expensive.
Even today, Brigadiers are senior field-grade officers, not junior generals (they wear colonel's rank insignia with an extra pip, not general's stars).