The capitalization of "Sie" was probably just because it was the beginning of a new line, it was probably meant as a complete sentence:
"Und von außen kamen sie in Scharen her."
I would recommend rephrasing the line "Take time for defeat" for a few reasons:
"Untergang" has a more nuanced meaning in German. It literally means to go under, but can also mean sinking, downfall, destruction, etc.
The phrase "take time for..." in English usually means to make time for something you want to do, whereas "take your time" means to do something slowly.
Since he is saying "Stirb langsam!" (die slowly) and "Nimm dir Zeit," it might be better to say something like "Take your time as you sink" (or "Take your time in the downfall/as you go under") instead of "take time for defeat."
*the original German had “und von aussen kamen Sie in Scharen her”, but the text had “Sie” at the start of a new line, making it ambiguous whether it’s meant to be “Sie” or “sie”, so I just went with the option that made sense to me contextually.