Mike, when night fell, moved away toward the castle, which lay about a quarter of a mile from the village. Approaching to within fifty yards of the gate, he sat down to watch. About eleven o'clock he heard the creak of the gate, and presently was startled by seeing two horsemen ride past him. "They must have muffled their horses' feet," he said to himself. "They are up to no good. I wish there had only been one of them." Mike slipped off his shoes and started in pursuit, keeping just far enough behind the horsemen to enable him to observe the outline of their figures. For half a mile they proceeded quietly. Then they stopped, dismounted, removed the cloths from their horses' feet, and remounting rode forward at a gallop. Mike's old exercise as a runner now rendered him good service. He could already tell, by the direction which the horsemen were taking, that they were bearing to the east of Edinburgh, but he resolved to follow as far as possible in order to see exactly whither they went. The road, or rather track, lay across a moorland country. The ground was often deep and quaggy, and the horsemen several times checked their speed, and went at a slow walk, one advancing on foot along the track to guide the way. These halts allowed breathing time for Mike, who found it hard work to keep near them when going at full speed. At last, after riding for an hour, the horsemen halted at a solitary house on the moorland, Here several horses, held by troopers, were standing. Mike crept round to the back of the house, and looked in at the window. He saw two English officers sitting by a fire, while a light burned on a table. Mike at once recognized in one of them the dreaded General Cromwell, whom he had seen at Drogheda.  
"What a fool I was," he muttered to himself, "to have come without my pistol. I would have shot him as he sits, and so wiped out Drogheda."
 
At the moment the door opened, and a trooper in Scotch uniform entered. "I have brought this letter," he said, "from Alan Campbell."
 
The general took the letter and opened it. "Campbell promises," he said to the other officer, "to open fire upon the detachment in the village with the guns of the castle as soon as we attack. One of the men who has brought this will remain here and guide our troops across the morass. He suggests that two hundred foot and as many horse should be here at eight to-morrow evening. All he stipulates for is that Colonel Furness, the Royalist who commands the enemy's detachment, shall be given over to him, he having, it seems, some enmity with Argyll. Furness? ah, that is the officer whom I sent to the Bermudas from Drogheda. We had advices of his having got away and captured a ship with other prisoners on board. A bold fellow, and a good officer, but all the more dangerous. Let Campbell do with him as he likes."
 
The other officer drew out an inkhorn and wrote, at Cromwell's dictation, his adherence to the terms offered by Alan Campbell. Cromwell signed the paper, and handed it to the messenger. Then the English general and his escort mounted and rode off. Campbell's retainers sat for half an hour drinking together. Then they came to the door. One mounted, and saying to the other, "I would rather have twenty-four hours' sleep such as you have before you, than have to ride back to Kirkglen to-night; the mist is setting in thickly," rode off into the darkness.
 
Mike kept close to him, until at last the man dismounted to follow the track where the morass was most dangerous. In an instant Mike sprang upon him and buried his dagger in his body. Without a cry the trooper fell. Mike felt in his doublet for Cromwell's letter. Placing this in his breast, he went a few paces from the path where he found that he sunk to his knees, the water being some inches deep over the bog. Then he returned, lifted the body of the trooper, carried it as far into the bog as he dared venture, and then dropped it. He placed his foot on the iron breastpiece, and pressed until the body sank in the soft ooze, and the water completely covered it. Then he went back to the horse, and taking the reins, followed the track until completely clear of the moorland country, where, mounting, he rode back to Kirkglen, and presented himself to Harry. The latter had, hours before, gone to bed, having posted strong guards around the village. He struck a light and listened to Mike's relation of what he had done, and ended by the production of the document with Cromwell's signature.
 
"Another debt to the Earl of Argyll," Harry said grimly. "However, although this proves the treachery of his kinsman, it does not convict Argyll himself, although the evidence is strong enough to hang any other man. Now, Leslie, what do you advise? Shall we send and seize the man left at the hut?"
 
"It is a doubtful question," Leslie answered, after a pause. "When Campbell finds that his messenger does not return before morning, he will like enough send others off to learn the reason why. If they find him gone, Campbell may suspect that his plan has failed and may send warning to Cromwell."
 
"At any rate," Harry continued, "we need not decide before morning. But at daybreak, Leslie, plant a party of men on the road and stop any horseman riding out. Let the sergeant in charge say only that he has my orders that none are to pass eastward. It would be a natural precaution to take, and when the news comes back to the castle, Campbell will not necessarily know that his scheme has been detected."
 
The next morning Leslie volunteered to go out with a couple of men and capture the guide, and arraying himself in his clothes, to take his place, and lead the Roundhead troops astray.
 
"Were the country other than it is," Harry said, "I would accept your offer, my brave Leslie, even though it might entail your death, for it would be difficult for you to slip away. But over such ground there is no need of this. Let the guide lead the Roundhead troops along the path. We will reconnoiter the morass to-day, and when night falls will so post our men as to open a fire on either flank of him as he comes across the track. Not more than four footmen can march abreast, according to what Mike says, and we shall surprise him, instead of he surprising us."
 
An hour later two horsemen rode out from the castle, but upon reaching the guard Leslie had placed were turned back. They returned to the castle, and a short time afterward a trooper rode down into the village with a note from Alan Campbell, demanding haughtily by what warrant Colonel Furness ventured to interfere with the free passage of his retainers. Harry replied that he had, as a military precaution, stationed guards on the various roads leading toward the enemy's quarter, and that they were ordered to turn back all, whomsoever they might be, who might seek to pass.
 
Alan Campbell returned a furious answer, that he should sally out with his garrison, and ride where he listed. Harry replied by marching fifty men up to the road leading to the castle, and by sending a message to Alan Campbell that, although he should regret to be obliged to treat him as an enemy, yet that assuredly if he strove by force to break the military rules he had laid down, he should be compelled to fire upon him. Leaving the detachment under charge of Lieutenant Long, and the main body in the village under that of Hugh Grahame, Harry, accompanied by Donald Leslie and Mike, rode off to reconnoiter the morass. They found that it was particularly bad at two points, while between these the ground was firm for a distance of twenty yards on each side of the track. Beyond the swamp was very deep for thirty or forty yards on both sides, and then it was again somewhat firmer.
 
Harry decided to post twenty-five men behind these quagmires. Their orders would be to remain perfectly quiet until the column, passing the first morass, should have entered the second; then, when Harry, with the main body, opened fire upon them there, they were to commence upon the flanks of the column.
 
Returning to the camp, Harry sent forty men with shovels, obtained in the village, to dig a trench, twelve feet wide, and as deep as they could get for the water, across the track, at the near side of the morass.
 
At nightfall, leaving twenty-five men under William Long in front of the castle, with orders to let none issue forth, and to shoot down any who might make the attempt, Harry marched out with the rest of his command. Crossing the ditch which had been dug, he led fifty forward, and posted them, as he had planned with Leslie; with twenty-five, he took up his own station behind the breastwork formed by the earth thrown out from the trench. The remaining fifty he bade advance as far as they safely could into the swamp on either side. Two hours later a dull sound was heard, the occasional clink of arms, and the muffled tread of many feet on the soft ground. The Roundhead infantry, two hundred strong, led the way, followed by their horse, the guide walking with the officer at the head of the column. When it approached within twenty yards of the ditch Harry gave the word, and a flash of fire streamed from the top of the earthwork. At the same moment those on either side opened fire into the flanks of the column, while the fifty men beyond poured their fire into the cavalry in the rear of the column.
 
For a moment all was confusion. The Roundheads had anticipated no attack, and were taken wholly by surprise. The guide had fallen at the first discharge and all were ignorant of the ground on which they found themselves. They were, however, trained to conflict. Those on the flank of the column endeavored to penetrate the morass, but they immediately sank to the middle, and had much ado to regain the solid track. The head of the column, pouring a volley into their invisible foes, leveled their pikes, and rushed to the assault. A few steps, and they fell into a deep hole, breast high with water, and on whose slippery bottom their feet could scarce find standing. In vain they struggled forward. From front and flank the fire of their enemy smote them. Those who reached the opposite side of the trench were run through with pikes as they strove to climb from it.
 
For ten minutes the desperate struggle continued, and then, finding the impossibility of storming such a position in the face of foes of whose strength they were ignorant, the Roundhead infantry turned, and in good order marched back, leaving half their number dead behind them. The cavalry in the rear had fared but little better. Finding the ground on either side was firm when the fire opened on their flanks, they faced both ways, and charged. But ere the horses had gone twenty strides they were struggling to their girths in the morass. Their foes kept up a steady fire, at forty yards' distance, into the struggling mass, and before they could extricate themselves and regain the path............