Verse 4 seems to have been heavily folk processed. Here is another take on it.

That brave and gallant youth have crossed the ocean
To free America of her division.
He landed at Quebec with all his party,
A city to attack both brave and haughty.

I don't expecially like the singular youth with the plural have. The last word is a good example of what happens in aural tradition. The three words (hardy, hearty, haughty) all sound sort of the same depending on the singer and all three fit into the line without altering the song very much. Here are some additional line and verse variants primarily from Edith Fowke and Alan Mills.

Brave Wolfe drew up his men in a line so pretty
On the Plains of Abraham before the city
The French came marching down, arrayed to meet them
In double numbers 'round, resolved to beat them.

Montcalm and this brave youth together walk-ed
On the Plains of Abraham, together talk-ed.....

The drums did loudly beat, with colors flying
The purple gore did stream and men lay dying
When shot from off his horse fell that brave hero
We'll long lament his loss that day in sorrow.

Brave Wolfe lay on the ground where the guns did rattle
And to his aide he said, "How goes the battle?"
"Quebec is all our own, they can't prevent it"
He said without a groan, " I die contented"

The song is a fairly accurate description of the battle of Quebec that took place on September 13, 1759. It proved to be a decisive event in the history of North America and perhaps the world. In 1755 the Acadians had been driven out of Nova Scotia and a year later the Seven Years War broke out in Europe and elsewhere. Britain bumbled around early and was not doing very well. But by 1759 Louisville, Fort Frontenac & Fort Duquesne had been taken by Britain. Montcalm had pulled back to Quebec for a last stand. The British fleet under Wolfe had layed siege to Quebec from below on the St Lawrence River. British scouts finally discovered a narrow way up the cliffs to the city and on the night of Sept 12 about 5000 men secretly took small boats down the river and scaled the cliffs to the Plains of Abraham. The battle was over quickly and both Wolfe and Montcalm were killed. The first verses reflect the fact that young Wolfe had become engaged to Kathrine Lowther shortly before sailing to America. The only real poetic license in the song concerns the horse that Wolfe was shot from. How did they get a horse up those steep cliffs?