The old adage that good fences make good neighbors is true out in the country where fences often serve to contain livestock rather than for decorative purposes. The problem with that adage is livestock is hard on fences. Properly braced a wire fence can be stretched tighter making it sturdier and less prone to stretching, sagging and other problems.
Select the fence posts that will require bracing. Generally, posts that will be under equal strain in opposite directions will not require bracing. Posts in the straight line of the fence are an example of this situation. Corner posts that will have stress in two directions not opposite of each other and posts at gates where there is only stress from the fence in one direction are examples of posts that will require bracing.
Set the corner or gate post. Use as large a treated wood post as possible in these situations and set it as deep as possible. A minimum sized post should be 8 to 10 inches in diameter set 3 to 4 feet deep although the size of the post and the depth it can be set are both controlled by the post hole digging equipment available to the fence builder. Tamp dirt around the post to firmly set the post in place.
Set a brace post 6 to 8 feet from the corner or gate post. Use the same size post and the same procedures as used on the corner or gate post. There are several bracing methods that can be used. The corner and brace post can be notched to accept a wooden brace that runs diagonally from the top of the corner post to the base of the brace post. Stretching the wire of the fence will put the greatest stress on the top of the corner post. The angled brace transfers some of that stress to the strongest part of the brace post.
Place the brace horizontally between the top of the corner and brace post. In this configuration a wire brace is used to pull together the top of the corner post and the bottom of the brace post. This creates a triangle, the strongest geometric figure, running from the top of the corner post to the top of the brace post, down to the bottom of the brace post and then back up to the top of the corner post. This system can be doubled with another wire brace running from the top of the brace post to the bottom of the corner post creating two triangles for strength. Make the wire braces from multiple strands of heavy smooth wire looped around the posts. Use a piece of wood as a lever to tighten the brace by placing it through the wire bundle and turning it. This will twist the strands of wire and tighten the brace.