If you are not familiar with how the Assyrian came down like the wolf on the fold, first read II Kings 18-19 (it’s also in Isaiah 36-37). Then read Lord Byron’s immortal take, even though the psalmist beat him to it by about 2500 years.
For Holy Saturday, it is the harrowing of hell.
“Notus in Judaea” (Psalm 75)
 In finem, in laudibus. Psalmus Asaph, canticum ad Assyrios.
Unto the end, in praises. A psalm for Asaph, a canticle unto the Assyrians.
 Notus in Judaea Deus; in Israel magnum nomen ejus.
Known in Judah, God; in Israel great His name.
 Et factus est in pace locus ejus, et habitatio ejus in Sion.
And it is made, in peace, His place and His habitation in Zion.
 Ibi confregit potentias arcuum, scutum, gladium, et bellum.
There He shattered the powers of bows, the shield, the sword, and war.
 Illuminans tu mirabiliter a montibus aeternis;
Brightening, You, marvelously from the eternal mountains;
 turbati sunt omnes insipientes corde. Dormierunt somnum suum, et nihil invenerunt omnes viri divitiarum in manibus suis.
they are a-turmoil, all the foolish in heart. They have slept their sleep and nothing have they found, all men, of riches in their hands.
 Ab increpatione tua, Deus Jacob, dormitaverunt qui ascenderunt equos.
By Your rebuke, God of Jacob, they have grown sleepy who mounted horses.
 Tu terribilis es; et quis resistet tibi? ex tunc ira tua.
You are terrible and who will make resistance to You? Thence Your wrath.
 De caelo auditum fecisti judicium : terra tremuit et quievit
Down from heaven audible You made a judgment; the earth shook and was quiet
 cum exsurgeret in judicium Deus, ut salvos faceret omnes mansuetos terrae.
when He arose in judgment, God, when He made safe all the gentle of the earth.
 Quoniam cogitatio hominis confitebitur tibi, et reliquiae cogitationis diem festum agent tibi.
For the meditation of man will make confession to You and the remnants of meditation, a feast-day will they make to You.
 Vovete et reddite Domino Deo vestro, omnes qui in circuitu ejus affertis munera terribili,
Vow and repay to the Lord Your God, all who in His circuit convey tributes to the Terrible,
 et ei qui aufert spiritum principum; terribili apud reges terrae.
and to Him who carries off the spirit of princes; to the Terrible before the kings of the earth.