I think it makes sense   The way the line is worded:  "The triple Tyrant:  that from these may grow"

As Andy mentioned, there are a lot of Biblical illusions in this poem and I would guess that identifying them is one of the challenges, (not one I would be good at).

L3, at least, I believe to be trochaic rather than iambic and has an extra syllable. At least part of that might have been avoided by using "E'en". 

It is unlikely, in those times, that Milton would have worked for Cromwell had he not been Protestant. We may not even have Paradise Lost but for Cromwell.

As far as Milton goes,  I pefer sonnet IX , To a Virtuous Young Lady.This is intresting though.  This is littered with Biblical illusions. One that jumps is the reference to a hundred fold, or the seed illustration in the scriptures. ----Andy

Norm -- please don't; this is where this stuff gets interesting! Most of my comments have an air of Devil's Advocate about them anyway, and I'd like for them to be taken in that light (although I won't concede any uncivility on my part). So if you choose to discontinue, then fair enough -- but I'd certainly enjoy hearing your thoughts.

James

'This poem cannot compete with Lycidas on the basis of pastoral imagery or on the tenets of Christianity.'

Certainly. No need to get uppity over my method of expressing what you go on to agree with. Perhaps you just look at 'pales in comparison with' in a more hyperbolic light than I do. It goes without saying that the poem is good: it's written by Milton. 

In terms of 'anger', I would suggest that

Blind mouthes! that scarce themselves know how to hold       
A Sheep-hook, or have learn'd ought els the least       
That to the faithfull Herdmans art belongs!       
What recks it them? What need they? They are sped;       
And when they list, their lean and flashy songs       
Grate on their scrannel Pipes of wretched straw,       
The hungry Sheep look up, and are not fed,       
But swoln with wind, and the rank mist they draw,       
Rot inwardly, and foul contagion spread:       
Besides what the grim Woolf with privy paw       
Daily devours apace, and nothing sed,       
But that two-handed engine at the door,       
Stands ready to smite once, and smite no more.

is far more potent in terms of harshness, especially with the added depth of melancholia. Just listen to the sonics in 'Grate on their scrannel Pipes of wretched straw,       / The hungry Sheep look up, and are not fed, / But swoln with wind, and the rank mist they draw, / Rot inwardly, and foul contagion spread'.

Incidentally, I didn't mean to even bring PL into the equation -- it hardly counts as 'mid-length'. Very little in literature in general matches up to PL, so it hardly needs mentioning.

And in political statement? 'Shame on you for killing those old-fashioned but decent Christian folk who are not idolatrous. I hope their martyrdom goes as an example to spread the faith.' Doesn't seem especially exciting.

The blood of the martyrs is the seed of the Church.
-- Tertullian

Which, alongside the Parable of the Sower, is of course the volta.

It's solid enough but pales in comparison to his mid-length poems like Lycidas in my opinion.

This poem is one where, I would say, some history does need to be known.
The subject is the massacre of Waldensians, a Christian church who promoted true poverty, public preaching and the literal interpretation of the Bible. Declared heretical, the movement was persecuted by the Roman Catholic church who were opposed to the translation and circulation of the Bible to laity. The massacre took place in the Italian Piedmont valleys in 1655 by the army of Charles Emmanuel II, the Catholic Duke of Savoy. The Protestant world was angered and Oliver Cromwell, then Lord Protector of England, protested. John Milton was his foreign secretary and poet. He dedicated this sonnet of Paradise Lost to the thousand of slaughtered Waldensians.
My guess is that the triple Tyrant would be referring to the Pope.

As far as mechanics of form are concerned, I found bumps in meter in L3, 8, 10, 11 and 14.

I like how he used additional rhymes in L9 and L11 – hills/they, still/sway.

That's my quick take.

nas, your quote, the Psalm, sheds some interesting light on the subject - thanks.

     Terence

On the Late Massacre In Piedmont

by: John Milton (1608-1674)

Avenge, O Lord, thy slaughtered saints, whose bones 
Lie scattered on the Alpine mountains cold; 
Even them who kept thy truth so pure of old, 
When all our fathers worshipped stocks and stones, 
Forget not: in thy book record their groans 
Who were thy sheep, and in their ancient fold 
Slain by the bloody Piedmontese, that rolled 
Mother with infant down the rocks. Their moans 
The vales redoubled to the hills, and they 
To heaven. Their martyred blood and ashes sow 
O'er all the Italian fields, where still doth sway 
The triple Tyrant; that from these may grow 
A hundred fold, who, having learnt thy way, 
Early may fly the Babylonian woe. 

Note: I have mentioned before that this sonnet is in my top ten of favorite poems. There is a lot to "chew" on in this one and it also will afford us the opportunity to look at the poetic mechanics of this sonnet since Milton takes liberties with the form (like Eliot and others). 

This one should give us opportunities to examine a poem of many levels -- interptretation, technique, history, and a lot more).

The discussions on the last two poems were excellent IMHO --- I learned a lot and gained insights with every post.