You don't need to stand on a hill, though that can work.
Here is what I do.
1) Archer Calvary is approaching slowly
Try to keep a small hill or rise in elevation between you and the enemy line. Keep moving to maintain this. Keep your men in line and close together by pressing 8.
If there is no elevation then draw a line, and press 6 over and over again to advance quickly. MAINTAIN YOUR LINE.
Once the calvary hits your line allow your men to attack freely, but as soon as they start to scatter order them back into a line.
The line is good, but it does prevent your men from ganging up on the enemy, so you want to alternate between charge and line depending on the situation.
Being in line can be bad, so alternate between the line and charge.
2) Non-Archer Calvary is approaching slowly
In this case get line of sight and hold the line and wait. (stay close to your spawn point and far from their spawn point).
Alternate between line and charge. Remember do NOT allow your troops to scatter!!
3) Calvary is approaching fast
Hold the line and then alternate between line and charge. (stay close to your spawn point and far from their spawn point).
A well commanded line of nords will munch through calvary. The key is commanding them correctly, and not getting shot yourself.
I play with normal damage and normal settings with 100 troop size (107% difficulty).
The main problem I have using ground forces to take out calvary is that I get shot or lanced. To avoid this I stay in the middle of my troop line, and if I can I stay near a tree, rock, or a horse. The horses make create barriers so keep your line, and yourself near the horses.
Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line, Charge, Hold the Line... VICTORY!!!
- Livonya