Remember the order
1) Movement
2) Unit attack
3) Fortification attack
The distance is set by the ballista in this case to 1600 yards (1400 base + 200 yards). Remember, distance is counted from the base speed, not modified speeds. Other thing to remember is if the speeds of the units are tied, defense always moves first. That is an important factor to remember in order to save your archers. I'm attacking a lvl 10 hill so all of their techs and all of mine are both set at 10. There are no fortified units so there is no step 3 for any of the rounds in this case.
Round 1 Movement
Defensive cav move forward 1500 yards (1000 + 50% from HBR)...No units in range so they move the full 1500
Offensive cav move forward 100 yards till they hit the defensive cav (remember, 1600 yard starting range)
Offensive pike move forward 100 yards
Defensive swords move forward 550 yards (275 + 100% from Compass)
Offensive sword moves forward 100 yards (to cav)
Defensive archers don't move (in range of archers)
Offensive archers don't move (^^)
Offensive ballista doesn't move (^^)
Offensive scout doesn't move (read combat mechanics)
Round 1 Unit Attack
Defensive cav attack the offensive cav (kills the offensive cav)
Defensive swords aren't in range of anything
Offensive sword attacks defensive cav
Offensive pike attacks defensive cav
Defensive archers attack offensive archers
Offensive archers attack defensive archers (kills defensive archers)
Offensive ballista attacks defensive cav
Round 2 Movement
Defensive cav don't move (in range of pike and swords)
Offensive pike don't move (in range of cav)
Defensive swords move forward 550 yards (moved 1100 yards now)
Offensive sword doesn't move (in range of cav)
Offensive archers don't move (in range of cav)
Offensive ballista doesn't move
Offensive scout doesn't move
Round 2 Unit Attack
Defensive cav attack offensive pike (kills the offensive pike)
Defensive swords aren't in range of anything
Offensive sword attacks defensive cav
offensive archers attack defensive cav (kills defensive cav)
offensive ballista attacks defensive swords
Round 3 Movement
Defensive swords move forward 350 yards (to the offensive swords)
Offensive sword doesn't move (in range of swords)
offensive archers don't move (in range of swords)
Offensive ballista doesn't move
Offensive scount doesn't move
Round 3 Unit Attack
Defensive swords attack offensive sword (kills the offensive sword)
Offensive archers attack the defensive swords (kills defensive swords)
No more defensive units so the battle is over.