<span>"Whose stern impassioned stress" is part of a line from America the Beautiful. This means that the people who are being referred to are having to work hard, but they are passionate about completing the task even though the work they are doing is stressful and taxing. In context of the song, this line refers to the work the pilgrims had to do to achieve progress.</span>
I think, and misspelled words, and grammar.
It is the last sentence of the intro paragraph.
