Another type of field fortification we could employ are flèches. A flèche (pronounced flash) is a small "V"-shaped work constructed with the pointed end facing the enemy. These small, temporary works provided protection for the forward positions and outer pickets. Flèches formed part of the outer works at Breed's Hill, and Captain Ewald writes of their use: " ... the enemy was forced back from one ditch to another up to an advanced flèche which lay almost under the cannon range of the fortifications ..."1
These can be made from piles of fascines (without or without digging up the dirt) or from piles of fence posts or rails. In the case of the latter, simple fences could be constructed beforehand and a scenario made of tearing them down to build a flèche. In the period, some fences were made by simply stacking up split rails in a series of connecting "V"s as Thomas Anburey relates: "... from the mode of constructing these enclosures in a zig zag form, the New-Englanders have a saying, when a man is in liquor, he is making Virginia fences ."2
A few felled bushes or tree trimming can also be pressed into service to make an abatis (ab' a*tis). The brush is simply piled in a row with the ends of the branches facing the enemy. The branch tips are then sharpened to create 18th-century barbed wire. Be sure to get permission from the event sponsor before building your abatis. We pulled apart a brush pile to make an abatis at Fredonia a few years back and got yelled at by the grounds keeper. I'm sure it was quite a site to see the fierce redcoats (with fixed bayonets) looking sheepish and poking their toes in the dirt while getting chewed out by some guy perched on a John Deere utility tractor!
2) Anburey, Thomas, Travels Through the Interior Parts of America in a Series of Letters by an Officer, New York Times and Arno Press, 1969, p. 324.