I feel not fair with these answers so I am just checking.
1. Caesar pitched camp two miles from the river.
Caesar castra dua milia passuum a flumine posuit.
2. He fortified the camp with a ditch fifteen feet wide and nine feet high.
(Is) castra fossá quindecim latós pedés atque válló novem altós (pedés).
I'm not sure, whether latus, altus should be accusative. Can some one explain as I am doubtful!
3. The camp of the enemy was distant by a great space.
Castra hostium spatió magnó aberat.
4. On the next day he hastened ten miles in three hours.
Proximó dié decem mília passuum tribus hórís properávit.
5. Suddenly the enemy with all their forces made an attack upon the rear.
Subitó hostés omnibus copiís (suís) impetum in novissimum agmen fécérunt.
(It would not be "viribus" right?)
6. For two hours the Romans were hard pressed by the barbarians.
Duás hórás á barbarís Rómání prémébantur.
7. In three hours the barbarians were fleeing.
Duábus hórís barbarí fugiébant.
In this question I don't know, what he means in the English. "for three hours" would make more sense to me.
Any help, corrections are as always greatly appreciated!
(laetissimé accipiuntur, puto...)