Sentence:  I <WSD>know</WSD> that I myself felt that it was a mortal shame for a man to be torn open by a British musket ball , as Isaac had been , yet I also felt relieved and lucky that it had been him and not myself . 
Meaning of the word marked with <WSD> tags:  be aware of the truth of something; have a belief or faith in something; regard as true beyond any doubt