The English campaign is set up for novice users to get a better understanding of gameplay, while the French campaign is much, much more difficult. As the English General, you will fight under several historic figures, such as the Black Prince and Henry V. As the French General, you will fight for Joan of Arc and the King.
this page over at the Slitherine website - it's incredibly detailed.
It will set you back $6.99, but for a game this in-depth, something tells me that you will get more than your money's worth out of it. Hit the widget below for download.
HISTORY Great Battles Medieval