Looks like the typist might have been an OCR program or not sure of grammar and spelling -- the 'tis's are "tie"s and the couplet in the last verse (I think they are three six-line verses) which reads:

I strike for the memory of long-vanished prearm;
I only shed blood where another shed tears.

makes no sense -- "prearm" should be "years", or possibly "dears" or even (farfetched) "fears". All the othe rcoupletsd are simple rhyming pairsd, and there's no such animal as a pre-arm. I think it was scanned in and OCR'd.

Any idea who the author was?

A