Gerusalemme Liberata recounts the climax of the First Crusade, when Godfrey of Bouillon conquered Jerusalem in 1099.
It can be interpreted as an epic poem (a sort of Christian Iliad), but in truth its interpretive keys are far more intricate than those of Homer's work.
First and foremost, the poem is the narrative of a purification, both collective and individual:

thus singing, the devout host unfolds and spreads in wide circles, directing its slow procession toward Olivet

( Canto XI, verse 10).
This holy advance collides, in bloody combat, with the Saracens and with the forces of evil: a struggle between supernatural powers of the underworld and the heavens.
The clashes between armies and knights form one of the poem's central threads, allowing Tasso to display a consummate mastery and knowledge of the art of war and dueling, imbued with a taste for the macabre that anticipates modern adventure cinema:

and between neck and nape he strikes the blow; severed the sinews and slit the throat, the spinning head fell down and stained its face with foul dust before the trunk could fall; the trunk remains (a wretched monster) seated in the saddle, but freed of the rein, wheeling and kicking wildly, the steed shakes it off

.
( Canto IX, verse 70).
Yet what a contrast between dreams of military glory and the harsh, cruel reality! In memorable verses, Tasso sings of the absurdity of war.
At the battle's end

there is no silence, nor any distinct cry, but a hoarse and muffled sound is heard: shudders of fury, murmurs of rage, groans of those who languish and those who breathe their last.
The weapons, once so joyous to behold, now made a grim and mournful show; the iron had lost its gleam, the gold its rays, and no beauty remained in their once-fair hues

.
( Canto XX, verses 51 and 52).
Alongside the epic component lies the elegiac and lyric dimension, made up of extended landscape and sentimental interludes.
It is the most luminous facet of the poem, pivoting upon woman—a figure who, for Tasso, is complex, richly nuanced, a mystery to be unveiled.
Erminia, a delicate Saracen maiden in love with Tancredi, a Christian knight, longs to become a warrior to remain near her hero:

ah, why did Nature and Heaven not make my limbs and breast as strong, that I too might exchange skirt and veil for cuirass and helmet

( Canto VI, verse 83).
Yet Erminia realizes that war belongs to men, and that she can only be a gentle wife:

unhappy Erminia flees, and her swift steed gallops across the earth

( Canto VI, verse 111).
And Armida, the true protagonist of the poem, is a sorceress, an enchantress, and a conqueror of men; yet when she beholds her Rinaldo—himself a Christian knight—her hatred turns to love:

but when she fixed her gaze upon him and saw how placidly he breathed....
from an enemy, she became a lover

.
( Canto XIV, verses 66 and 67).

It is precisely the portrayal of the poem's women and their star-crossed love for Christian knights that reveals the complexity of Tasso's universe.
He aspires to be the poet of the Counter-Reformation, of steadfast faith unclouded by doubt; yet one senses how deeply the poet loves the feminine realm, probing its torments and sentiments, just as he harbors a predilection for the vanquished and the infidels.
In contrast to the rigid, impersonal Christian knights (Goffredo, Tancredi, and Rinaldo), stand complex characters endowed with profound humanity: the tender Erminia, the ill-fated Armida, the valiant Saladin, and the fierce Argante.
These are living figures, fraught with doubt, affection, and memory.
This is Tasso's spiritual world, mirroring his own anguish:

I shall live amidst my torments and my cares, my rightful Furies, frantic and wandering; I shall dread the dark, solitary shadows that bring my first transgression before me, and of the sun that unveiled my misfortunes, I shall abhor and loathe the sight.
I shall fear myself; and ever fleeing from myself, shall have myself forever near

.( Canto XII, verse 77).
Here is the modern, pre-Romantic, and existential Tasso, with his passion for nocturnal scenes:

meanwhile night rises, and beneath its wings the sky shrouded the boundless plains; and sleep, the soul's repose, oblivion of woes, with flattering touch lulled cares and senses into rest

yet there is no peace, “for the cruel fury appears before him in dreadful phantoms, striking him with terror” ( Canto VIII, verses 57 and 59).

Why read it? It is a long poem, at times tedious, written in demanding verse that is dense and convoluted.
Yet when Tasso breaks free from religion, from faith, from what must be said, and gives rein to his inspiration, a musical and profound lyricism captivates the reader.

Jerusalem Delivered