The defenses built by the settlers and by the military in the Potomac River basin, regardless of style or type, were all known as forts, the term embracing stockades, blockhouses, forts, stations, posts, log cabins, stone houses, cellars and in fact, any and all other positions that could be strengthened and fortified so as to offer protection form enemy attack. The military authorities in VA, MD and PA generally constructed only forts or stockades as these installations furnished the greatest protection to the largest number of people in a given region. The settlers usually erected stockades and blockhouses, but they were not adverse to the use of any other position that might furnish a haven in time of danger.
The fort was the strongest of these defenses. It was constructed by the armed forces according to plans formulated over many years by leading European military engineers. The place usually consisted of a double outer wall made up of heavy palisades closely fitted together. The space between the two perimeter walls was then filled with dirt, gravel and stone, thus making a solid, bullet-proof obstruction. If the nature of the ground allowed, the fort was generally surrounded by a deep ditch with rampart and parapet. It was usually square in form with diamond-shaped bastions at each of the corners. Some had redoubts and all had sally posts. Sometimes the outer wall was constructed of stone, as at Fort Frederick in MD. All the forts were defended by artillery consisting of howitzers, from four to eighteen pounder cannon and swivel guns capable of firing clusters of lead balls as the musket fired buckshot.
A fort was a staunch position and if resolutely defended, it could be taken only by a strong force with the aid of artillery. Cumberland and Frederick in MD and the two Loudouns, one in VA and the other in PA, appeared to be the only true forts erected in the Potomac River basin during the Indian wars, although Benjamin Chambers' place in PA was of such strength that it nearly attained to the status of a fort. Because it was built of stone, Fort Frederick was considered the strongest position on the Potomac and its tributaries.
Within the fort, barracks were constructed capable of housing, in some instances, as many as five hundred soldiers. Storehouses, stables and other structures were erected as needed. A well was sunk within the enclosure to furnish a constant supply of water. There was also room for a parade ground, officers' quarters and sometimes cabins to house settlers who might be gathered in the place during dangerous times. Most of the true forts were large and thus capable of sheltering many people. Cumberland and Frederick each enclosed approximately one and one half acres.
The stockade was the most common defense. As noted, it was favored by both the settlers and the military. It consisted of a square or rectangular wall composed of upright logs called palisades which were planted in a trench three to four feet deep, the logs extending from twelve to eighteen feet above the surface of the ground, and sometimes enclosing as much as one acre of land. The palisades were generally shaved to a sharp point on the tops so as to entangle and pierce any enemy attempting to climb over them. A catwalk was constructed on the inside of the wall four to five feet below the crest to permit riflemen to fire over the stockade or through loopholes at any point around the perimeter. Within the enclosure, barracks, storehouses, cabins, stables and other structures were built for the use of the garrison and any settlers congregated therein. Four, but more commonly two, blockhouses, sometimes called bastions, were built at the corners of the stockade, their purpose being to give the defenders an opportunity to shoot at any enemy that might have gained a position close to the stockade wall. The corner blockhouses were two-storied, the upper story projecting about two feet beyond the palisades, thus enabling the garrison to fire along the outer wall. The stockade and the added advantage of offering a have to the settlers' livestock when the Indians were about. In rare cases, artillery was mounted in or along the stockade. A stockade could be made very refined, attaining nearly to the status of a fort. Pleasant, rebuilt Seybert, both in what is now WV, and McDowell in PA, were examples of elaborate stockades.
The blockhouse was a two-storied log structure with the upper floor projecting about eighteen inches out and over the lower, thus giving the defenders the opportunity to fire down upon any enemy that might have gained a position close to the wall. The blockhouse was not surrounded by a stockade, but it contained many portholes so that the defenders might fire upon the enemy in any direction. In a sense, all the settlers' cabins were blockhouses, as each was capable of making a defense in case of Indian attack, but few cabins were originally built with the idea that they might serve as a blockhouse if attacked by the savages. The blockhouse, built purely for defense, was uncommon on the frontier in 1755. Twenty years later along the Ohio River and its tributaries, it became much more popular as a means of protection. Its main defect was its inability to house many people, but with sufficient defenders, the blockhouse could be made a very strong position.
A station or post, the terms being used interchangeably in most instances, was not a fortified place in the sense that a fort, stockade or blockhouse constituted a fortification. At a post or station, troops might live in tents of in hastily constructed log cabins or lean-tos erected as protection against the elements. breastworks and trenches were sometimes built around the camp as a defense against sudden onslaughts of the enemy. Captains John Ashby and William Cocke, together with their rangers, lived in camps of this nature for several weeks on Patterson's Creek until the completion of forts Ashby and Cocke in the autumn of 1755. Troops sent to the Forks of Cacapon were stationed in a mill building until Fort Enoch was completed, while soldiers posted to the mouth of Sleepy Creek housed themselves in whatever cabins they could find until a fortification could be built. Before a fort, stockade or blockhouse was constructed, the place was a station at which troops were posted, and thereafter, it was usually referred to as a fort.

Following the defeat of Braddock's army, the governor of PA appointed Benjamin Franklin to take charge of the frontier defenses in that province, to raise troops and to build forts for the protection of the settlers. Franklin described the construction of a stockade:
  The next morning our fort was plann'd and mark'd out, the circumference
  measuring four hundred fifty-five feet, which would require as many palisades to
  made of trees, one with another, of a foot diameter [sic] each. Our axes, of which
  we had seventy, were immediately set to work to cut down trees and, our men
  being dexterous in the use of them, great dispatch was made. Seeing the trees
  fall so fast, I had the curiosity to look at my watch when two men began to cut at a
  pine; in six minutes they had it upon the ground, and I found it of fourteen inches
  diameter. Each pine made three palisades of eighteen feet long, pointed at one end.
  While these were preparing, our other men dug a trench all round, of three feet deep,
  in which the palisades were to be planted...when they were set up, our carpenters
  built a stage of boards all round within, about six feet high, for the men to stand on
  when to fire thro- the loopholes.
In fixing the location of a fort or other defensive position, several factors had to be considered. First, the place must not be so positioned that higher ground in the vicinity commanded it, thus giving the enemy the opportunity to shoot over the outer wall into the stockade or fort, or down through the roof of the blockhouse or barracks. In a rugged, mountainous country as found in the drainage basin of the Potomac, such places were difficult to locate. As a consequence, numerous stockades were erected with that disadvantage, a few examples being Forts Cumberland, Ashby, Pearsall and John Parker.
Water was an indispensable item. In addition to the manifold human and animal needs, water was necessary to extinguish fires that the savages were almost sure to set during their attacks. A spring within the stockade or in the cellar of a blockhouse ideally took care of this problem, as was the case at Forts Chambers, Edwards, Cresap and Rhodes. But springs were difficult to find that were not overlooked by circumjacent hills, or there were other drawbacks that made their locations unsuited as a defensive position. A small stream flowing through a stockade would appear to solve the water problem, but these runs generally coursed through narrow, precipitous hollows overlooked by surrounding high ground, making them unsatisfactory for fort purposes. IF the defense was placed along a river or creek, it could be subject to flooding upon any material rise of the stream. The best method found to insure a constant water supply was to sink a well within the stockade or fort and this was done in many places, including Forts Cumberland, Frederick, Kuykendall, and Loudoun at Winchester. All the defenses of whatever type had barrels of water constantly filled an ready for use about the premises.
If the plans called for the construction of a fort or stockade, the nature of the ground upon which it was to stand must be examined. The soil in the vicinity should be such as to allow easy excavation for a trench in which the palisades were to be planted. Soil underlaid with rock or hard slate could make it virtually impossible to dig a ditch with he tools available to the frontiersmen. Black powder was on hand for blasting, but that procedure was time consuming and expensive and only to be resorted to as a last expedient. Colonel Washington's plans for Fort Loudon at Winchester called for a deep ditch to entirely surround the place, but the limestone ground at the fort site made the necessary excavation impossible. The first place selected upon which to erect Fort Loudoun in PA was rejected by Colonel John Armstrong because the rocky nature of the soil prevented a trench being excavated in which to set the palisades and in addition, the spot was overlooked by adjacent hills.
To a lesser extent, the location should be reasonably near a supply of timber of the right size so as to assemble the palisades which made up the stockade, and which consisted of logs twelve to sixteen inches in diameter at the base. If time permitted, the palisades were flattened on two sides by the use of a broadax, thus allowing them to fit closely together when standing upright in the ditch. In some instances the logs or palisades were split. Two were then set up side by side with the split surfaces facing in a while a third was set up facing out so as to cover the joint or bread, thus making a wall which was impervious to musket fire. Whenever trees of the proper size were found, they were generally cut without considering their species. The durable, rot-resisting trees such as locust, cedar and chestnut, were used if they were straight, of the right size and handy to the axeman, but there appeared to be no special effort to secure these woods alone. Since they were generally the more plentiful, most of the stockades erected during the war consisted of palisades of pine and the various species of oak. These logs might stand embedded in the ground for a period of five to ten years without decaying, a time span which the military and the settler as well probably considered sufficient to see the war to a conclusion. The failure to use durable woods would seem to explain in part at least why the stockades disappeared so quickly following the termination of the war. But any palisade, regardless of the kind of tree from which it was taken, so long as it was of reasonable diameter, could stop the round musket and rifle balls fired into it by the enemy. Made of soft lead, these balls expanded considerably upon impact, thereby inhibiting deep penetration.