The Battle of Sedgemoor (or Weston Moor) Monday 6th July 1685.

Monmouth had failed to take Bristol and had steadily retreated back towards Bridgwater.  He was tactically bankrupt and in danger of losing his army through desertion.  Receiving some local intelligence he siezes the only viable option left - a dangerous night attack against the Royal Army now camped upon the moor outside Westonzoyland.
The rebel forces marched out of Bridgwater along the Bristol road in the dead of night and reached the lane leading to the moor without being spotted.  The Royal forces had a cavalry unit stationed in and around Chedzoy, but they failed to see or hear the rebel forces marching along the road.  However, upon reaching the Langmoor Rhyne the local guide leading Monmouth missed the crossing point and the rear echelons of the army crashed into the now stalled front elements.  This is probably when the Oxford Blue cavalry heard the rebels and gave the alarm by firing at the enemy. 
The first combat
The small 150 strong cavalry unit attempted to block the advance of the rebel forces by firing pistols and carbines, then retreating a short distance and firing again.  Meanwhile a trooper is sent to wake the camp.  The soldiers form up in pre-arranged places along the Bussex Rhyne (the ditch protecting the exposed moorside flank).  Monmouth realises that the element of surprise is lost and orders the cavalry under Lord Grey to ride with all speed to the enemy camp and try to find the bridges that cross the Bussex Rhyne  so that they can fall on the camp before they are fully awake.  The foot units also try to run across the dark uneven moor, so losing all formation in the process.
Note: Rebel forces are Blue and Royal forces are Red. Units represent foot, horse and artillery.
 Rebel cavalry reach the Bussex Rhyne
The Royal forces are already forming up by the time Grey arrives at the rhyne.  Splitting into two the rebel cavalry searches in both directions for the elusive bridges, or plungeons, across the Bussex Rhyne.  Grey, with the main body is fired upon by the First Foot Guards.  The horses are untrained and bolt uncontrollably back the way they had come.  This unfortunately sends them through their own infantry further disrupting them.
The other smaller cavalry force finds the upper plungeon, but it is protected by Royal cavalry and a brisk fight ensues.
The flight of the waggoners
The final damage done by the fleeing horse is that they tell the men who were with the wagons at the entrance to the moor, that all was lost.  Consequently the waggoneers ran also, therefore, no ammunition re-supply would reach the rebel forces.
Meanwhile out on the moor, the Red Regiment commanded by Wade reaches the Bussex Rhyne and reforms after the run across the moor.  The three rebel cannons begin firing to the left of the Red Regiment.  The Yellow Regiment under Col. Matthews arrives to the left of the cannons.  All units begin firing muskets at the now formed up Royal forces.  This spells disaster for Monmouth, as if he cannot get his men into close combat with the enemy before they are fully mustered then the superior firepower and cavalry of the Royal troops will eventually win the day.
Unfortunately, this proves to be the case.  Once the rebels begin to fire and to receive fire they will not cross the rhyne.
The spirited attack by the rebel cavalry under Capt. John Jones at the upper plungeon is finally repulsed and the survivors standby in support of the rebel foot units.
The Rout
Dawn begins to break and the Royal cavalry, who were stabled in the village, plus those under Col. Ogelthorpe, who were out on Knowle Hill watching the Bristol Road, muster ready for a counterattack.
When the daylight is enough to prevent friend attacking friend, the cavalry launch repeated attacks upon the rebel regiments.  By this time most of the rebel musketeers are low on powder and shot so are unable to effectively kill the enemy horsemen.  The defence falls to the stout pike and scythe armed men.  This defence successfully beats off the enemy horse.  However, The Royal infantry now cross the rhyne and a some of the Royal cannons are at last dragged over from the artillery park on the Bridgwater road.  The massive firepower silences the rebel cannons and cuts swathes through the tightly packed foot formations.  Eventually, the rebels break and run.  There follows a day of isolated skirmishes and slaughter of the rebels.  Only Major Wade and some of the Red Regiment put up a successful fighting retreat and make it back to Bridgwater in some semblance of order.
The last battle on English Soil
Monmouth escapes the battle only to be captured a few days later and then beheaded on 15th July.  The people of the West were to suffer the well known 'Bloody Assizes' under the jurisdiction of Judge Jeffreys. 
So ended the last battle on English soil.