Worth noting that the Portuguese were being trained by the British, who had adopted the practice of "dropping packs" before going into action since the replacement of the satchel/tournister style of pack with the more conventional backpack shortly after the SYW/F&IW. On that basis, I would go for no backpacks (contrary to what you have been told so far), but full "fighting order" of breadbag, water bottle, bayonet scabbard (and short sword, where appropriate).