Try saying “…our forefathers were not the strong leaders that most people imagine due to their lack of discipline, experience, and decision making abilities that resulted in numerous failures in the battles of the Revolutionary War.”

What you have given is a topic sentence – telling what your essay is going to be about.

If you want to make a thesis statement out of it, you will have to say something like:

In the war of 1776, history has credited out forefathers with being disciplined, experienced and adept at decision making, but the fact that they lost most of their battles during the Revolutionary War throws doubt on that assumption.

Now – since there was both a winner and a loser in the war of 1776, you have to identify which side you are refering to, and then back up your statement with examples, quotes, references and all that other good stuff that makes for such interesting footnotes.