There is no 'piracy' order as such in Austerlitz. If your fleet consists solely of
warships and meets a ship of nation to which you have a neutral relationship
towards, then they'll become privateers, hoist the jolly roger, and attack!
There aren't any shades of neutral in the game, so if your good and noble
captains come across a ship of a country that your majesty is frowning upon,
then they decide to do a little frowning themselves - with cannon balls...
Your pirate fleets must consist solely of warships, however,
which means that all you have to do to avoid catastrophic losses when moving a
warfleet and possibly engaging a larger foe is to include a merchantmen.