Ryan is right.
the SAFEST WAY would have been to use a class. Though it’s a pain to have to add that mark up. Still, for the sake of IE.
.stanza .first{text-indent:-2em;}
.stanza span{display:block}
.stanza br{display:none}
.stanza{margin-left:2em}/*use a margin left IF YOU dont want the text to break out of the paragraph box}
<p class=“stanza”>
<span class=“first”> Your first line of verse. it wont matter if it wraps</span><br>
<span>the edge and position of the the verse</span><br>
<span>Will be controlled by the class: stanza</span><br>
<span>btw, the display:none for the BRs is in case is in a browser thats not getting CSS</span>
</p>
I dunno if a block element would have been semantically correct here.