Canto XVII. There she joins the Christians' enemies, declaring she dreams of naught save slaying Rinaldo, and takes an important part in the review which the poet describes minutely. To compass her ends the artful Armida, whose charms have so lavishly been displayed that they have fired every breast, promises to belong to the warrior who will bring her Rinaldo's head. Meanwhile this hero has returned to Palestine, and is met by the wizard, who, after reproving him for his dalliance, gives him wonderful armor, and exhibits on the shield the great deeds of ancestors of the Duke of Ferrara.

Canto XVIII. Newly armed, Rinaldo now returns to the crusaders' camp, apologizes to Godfrey for breaking the rules of the crusade, relates his adventures, and, after humbly confessing his sins, starts forth to brave the spells of the magic forest. Not only does he penetrate within its precincts, but, undeterred by all Armida's enchantments, cuts down a tree, although, in hopes of staying his hand, her voice accuses him of cruelly wounding her! No sooner has this tree fallen than the spell is broken; so other trees are cut down without difficulty, engines built, and all is prepared for a new assault on Jerusalem.

Godfrey is particularly eager to make this new attempt immediately, because a carrier-pigeon has been caught bearing a message from the Egyptians to the Sultan of Jerusalem, apprising him that within five days they will come to his aid. During this assault of Jerusalem, a sorcerer on the walls, working against the Christians, is slain by a rock.

Soon after, thanks to the efforts of the Crusaders, the banner with the Cross floats over the walls of Jerusalem!

Then raised the Christians all their long loud shout
Of Victory, joyful, resonant, and high;
Their words the towers and temples lengthen out;
To the glad sound the mountains make reply:

* * * * *

Then the whole host pours in, not o'er the walls
Alone, but through the gates, which soon unclose,
Batter'd or burnt; and in wide ruin falls
Each strong defence that might their march oppose.
Rages the sword; and Death, the slaught'rer, goes
'Twixt Wo and Horror with gigantic tread,
From street to street; the blood in torrents flows,
And settles in lagoons, on all sides fed,
And swell'd with heaps on heaps of dying and of dead.

Canto XIX. Tancred, scaling a fortress, meets and slays Argantes, receiving at the same time so grievous a wound that he swoons on the battle-field. Meantime Godfrey has sent a spy to the Egyptian camp to find out whether the army is really coming on to Jerusalem. This spy, meeting Erminia there, induces her not only to reveal all the Egyptians' plans (including a plot to slay Godfrey), but to go back with him. While they journey along together to rejoin the Christian forces, Erminia relates her adventures, saying that while she was playing shepherdess, some freebooters seized her and carried her to the Egyptian camp, where she was placed under Armida's protection. Her story is just finished when they perceive what appears to be a lifeless warrior. By the red cross on his armor the spy recognizes a Christian, and further investigation enables him to identify Tancred. Erminia—who has owned she loves him—now takes possession of him, binds up his wounds with her hair (!), and vows she will nurse him back to health.

Canto XX. Warned by his spy that the Egyptians mean to send sundry of their number to mix, during the battle, with his body-guard and kill him, Godfrey changes the ensigns of his men, and thus discovers the conspirators, who are promptly put to death. Seeing the Egyptian army advance, Godfrey, in a stirring speech, urges his men to do their best for the Holy Sepulchre, and thereby stimulates them to fight so bravely that many of them lose their lives. Among the slain are Gildippe and her husband, who, having fought together side by side throughout the campaign, die together and are buried in the same tomb. The other party, however, is far more unfortunate, for the Saracens lose the sultans Aladine and Solyman, the former slain by Godfrey and the latter by Rinaldo.

Meantime Armida, wavering between love and hate, tries to shoot Rinaldo, then flees, but, a little later, seeing him slay Solyman, she tries to kill herself. It is at this moment that Rinaldo approaches her, and offers to marry her provided she will be converted. Not only does she now promise conversion and marriage, but accompanies Rinaldo back to the camp.