How was the crossing to France for the horses?

From the text:

As they tended us in our stalls the troopers joked and laughed together as I had never heard them before. And we were to need their confidence around us, for it was a stormy crossing and many of us became overwrought and apprehensive as the ship tossed wildly in the sea. Some of us kicked out at our stalls in a desperate effort to break free and to find ground that did not pitch and plunge under our feet, but the troopers were always there to hold us steady and to comfort us.