subtile engines > cunning engines of warfare beat from battery > beaten back from the attack
3 With greedy force he gan the fort assail
greedy > eager, reckless gan > did
4 Whereof he weened possessed soon to be,
Whereof > Of which weened > supposed [himself]
5 And win rich spoil of ransacked chastity. 6 Ah heavens, that do this hideous act behold,
hideous > odious
7 And heavenly virgin thus outraged see, 8 How can you vengeance just so long withhold,
vengeance just > [just vengeance]
9 And hurl not flashing flames upon that paynim bold?