As the game is set at the "end" of the Napoleon period, it would be logical that the Spanish fight alongside the British. Well, this is not true, they didn't recreate a specific period of the Napoleonic Wars, I know this because I asked Refleax and he answered that.
Oh ok, I heard that the game was set in 1812, but I wasn't sure, thanks for the info!
And judging by the uniforms it could be somewhere between 1802-1815, I couldn't say you because the British and French uniforms looks very similar in all these Napoleonic periods[...]
As you can see in the game, the "Fusilier" of the French faction (The 85e actually) has a "shako".
But, historically, Napoleon decided to replace the bicorne of the French infantry by a shako in 1806. The shako was simply not used by the Frenchies before this date.
So, if you follow the historical suggestion, the game is set between 1806-1815.
BUT, anyway, I would love to see the Spanish added to the game.