Allegedly, Saddam has given battlefield control of chemical weapons to his field-level commanders. This means, in effect, that if they want to use chemical weapons against an invasion, they can do. This report comes from the Pentagon, so it may or may not be true - it does, however, seem likely.

More worryingly, Saddam has told his commanders to be ready for 'the last battle'.

Combine the two, and you've got a distinct possibility of chemical attacks against Allied troops. Less likely (but with x-hundred commanders in charge of their own weapons, still possible), there's the chance that Iraqi civilians or surrendering soldiers will be gassed.