Good ends and corners are the key to strong fences. Every end and corner post that isn't holding its own means a sagging fence, and most likely some much visitors in the corn patch when they're lease welcome. It will pay you to have good fences. Here are some hints on howto build them- with the least possible work.
"Fence Ends - Corners,"
Iowa Farm Science: Vol. 2
, Article 4.
Available at: https://lib.dr.iastate.edu/farmscience/vol2/iss5/4