Not that I speek welsh, but I am bored and a little googling turns up a few of things...

rhyfel means 'war'
tawelwch means 'silent'
Dydyn ni ddim defaid = 'we/they are not wolves'
Dydyn ni ddim blaidd = 'we/they are not sheep'
calon seems to mean 'pure' or 'honest'
pawb means 'everybody'
heddwch is a place

So by filling in the blanks something like this...

No war ...
The war is silent
We are not wolves
We are not sheep
everybody in heddwch is pure

I wonder if that is even close