The Destruction of Sennacherib is written in quatrains using a very distinctive rhythm. The effect is of a lively, vibrant poem but this is at odds with the tragic subject. This is where the power of the poem lies for many readers – the contradiction of the form and content can be seen as echoing the contrast between the might of a great army and the tragedy of war.
The rhythm of the poem is also straightforward and regular which makes it very easy to read, though not necessarily to understand. This particular rhythm is often used in comic and light verse, so the fact Byron chose it for a poem about war and death is striking. Some readers see the regular patterning of the rhythm as echoing the hoof beats of the horses which the soldiers would have been riding. The regular rhythm of the poem is further emphasised by the fact that each line is end stopped and that about half of the lines start with the word 'and'. The use of ‘and’ in this way serves to drive the story forward in the same way the mounted soldiers are charging.
The poem benefits from being read/heard aloud.
Some of the vocabulary is deliberately archaic (eg 'strown', 'wax’d') and some of the word order also seems old-fashioned (eg 'their hearts but once heaved' rather than ‘their hearts heaved once’). This echoes the syntax found in the original Biblical story and thereby suggests a particular time and a place.
Much use is made of similes particularly in the early part of the poem (eg 'the sheen of their spears was like stars on the sea'). In the descriptions of the Assyrian army (both alive and dead) they are compared to elements of nature such as forest leaves or the surf of the waves. This is highly-effective and suggests that while mankind can easily be destroyed, nature will endure.
Byron also makes good use of alliteration, for example: