Your sources look more convincing than mine...
I just readed in Knötel's Handbuch der Uniformkunde: Die militärische Tracht in ihrer Entwicklung bis zur Gegenwart; It says about the French shakos (page 15:
"1804 wurde der Tschako eigeführt, doch dauerte es noch lange, bis die Truppe damit versehen war. Im Feldzuge 1806 trug die Linieninfanterie noch den Hut."
What Knötel says, is that the shakos were introduced in 1804, but that they were only used after a long time; In the 1806 campaign the hat (bicorne) was still used (although I believe at least some units wore shakos then, according to some drawings).
Anyway, I'll leave it to Quintillius to decide what to do.
I just readed in Knötel's Handbuch der Uniformkunde: Die militärische Tracht in ihrer Entwicklung bis zur Gegenwart; It says about the French shakos (page 15:
"1804 wurde der Tschako eigeführt, doch dauerte es noch lange, bis die Truppe damit versehen war. Im Feldzuge 1806 trug die Linieninfanterie noch den Hut."
What Knötel says, is that the shakos were introduced in 1804, but that they were only used after a long time; In the 1806 campaign the hat (bicorne) was still used (although I believe at least some units wore shakos then, according to some drawings).
Anyway, I'll leave it to Quintillius to decide what to do.