When British troops landed in India the residents, who spoke unstressed tongues, noticed a similarity between the "Left! Right!" marching cadence and the binary stresses of the English language. We accept the alternating stresses but why do we describe our speech as iambic as opposed to trochaic?
Part of the reason is in the effect of pronouns and articles on our subject-verb-object pattern:
"She saw | the boy."
Another reason is that ending on an accented syllable sounds more momentous, decisive or conclusive. Trailing off seems tentative, wistful, or uncertain. Thus, our poetry is iambic (de-DUM) or, occasionally, anapestic (de-de-DUM), and very rarely trochaic (DEM-de), dactyllic (DUM-de-de), or amphibrachic (de-DUM-de).
What do we do when we want to finish with a flourish? In sonnets we go from ending lines with distant/alternating rhymes to a couplet. Typical would be the ababcc scheme in this sestet:
Come autumn, combines comb the fields
to harvest gold canola oil
for toast before November yields
its cold. Like whitened coffee, soil
beneath integument snow extols
the blood and bone of remnant souls.
A less formal approach is to use extra stresses. In iambic work this creates a "Ta-Da!" effect, often as part of a double iamb. For example, we note the last line of "Kemla's Aloha":
You showed me home is a person not a place.
I watch as time collapses in your wake,
as every story, fully told, can trace
a common path, each stream to the same lake.
A more elaborate technique is classical diaeresis, ending a poem with a word in the verse's cadence. For example, the first stanza of the iambic pentameter "Beans" ends with an iamb; all previous disyllabic words are trochaic.
September came like winter's ailing child,
but left us viewing Valparaiso's pride.
Your face was always saddest when you smiled.
You smiled as every doctored moment lied.
You lie with orphans' parents, long reviled.
Hand this text to someone and have them read it aloud. Notice how "reviled" sounds like a finale? This parallels the finality of the parents' death. By contrast, the second stanza uses the spondaic approach, creating a sense of lingering consequence.
As close as coppers, yellow beans still line
Mapocho's banks. It leads them to the sea;
entwined on rocks and saplings each new vine
recalls that dawn in nineteen seventy three
when every choking bastard weed grew wild.
The stanza contains two iambs, "entwined" and "recalls", but that final line begins with, arguably, three pounding iambs ("ev'ry choking bastard"), setting up another instance of diaeresis, but the slightly less conclusive spondee, "grew wild", leaves on a more ominous note.
The first thing we should learn about any technique is when not to use it.