How would you critically appreciate Seamus Heaney's "Dedicatory Poem from Wintering Out"?

As is well-known, Seamus Heaney originally intended that his next collection of poem would be titled after a line from the poem “The Tollund Man”: Wintering Seeds.  The period is the early 1970s, and Heaney is preparing to return to his native Ireland from a temporary position at the University of California, Berkley.  Upon returning to Ireland in 1971, he settled first in Belfast and then, in 1972, moved to Dublin.  His original collection of poetry was soon expanded from 72 to 80, and the title of the collection was changed to Wintering Out, a phrase generally intended to suggest a period of hunkering-down through the months of brutally cold weather in anticipation of the spring to come.  The expansion in number of poems and title change are attributable to Heaney’s dismay at the scale of violence developing in Ireland.  What came to be called “the Troubles,” this was a seminal period in northern Irish history in terms of the increase in rage among the region’s Catholics against British/Protestant control, and the corresponding suppression of anti-Protestant demonstrations by British troops.  The violence reached its apotheosis on January 30, 1972, when British troops fired on demonstrating Catholics, killing 14 and wounding another fourteen.  “Bloody Sunday,” as the day has since been known, resounded deeply with Irish Catholics and remains a rallying cry.  This was the context in which Heaney was moved to write additional poems for his latest collection.  He went from celebrating the notion of rebirth through reference to the seeds found in the stomach of the 4th Century corpse discovered in Denmark to suggesting that it was time to lay low and ride out the storm.

“The Tollund Man” was not intended as a simple recognition of an ancient mummy.  Rather, Heaney employed the corpse as a metaphor for the decaying old ways characterized by the sectarian violence raging across Ireland and the seeds found in its stomach as symbolizing the birth of a new day.  As one reads through Winter Out, however, one clearly sees the evolution of a poet from optimist to pessimist.  Hence, in “Anahorish,” Heaney provides scenery to denote a sense of tranquility:

“My 'place of clear water,'
the first hill in the world
where springs washed into
the shiny grass

and darkened cobbles
in the bed of the lane.”

In “Wedding Day,” trepidation begins to seep into his poetry, as a day normally associated with joy is instead grounds for dread:

“I am afraid. . .
Sound has stopped in the day
And the images reel over
And over ...”

And, once again, in “The Tollund Man,”

“Out there in Jutland
In the old man-killing parishes
I will feel lost,
Unhappy and at home.”

Melancholy sentiments emanating from Ireland hardly rare; a country of incredible physical beauty, it has been the sight of innumerable disasters and conflicts.  Seamus Heaney’s poetry reflected the descent of Ireland into a protracted period of horrendous violence. 

What is the summary of the Dedicatory Verse in Seamus Heaney's Wintering Out?

Summarizing the Dedicatory Verse in Heaney's Wintering Out, his third published poetry collection, works better if you start from the end then go back to the beginning. The little destinies that are executed with competence (as a mechanical engineer or a railway porter are competent) and that are filled with coherent miseries (those agonies of life that one is fully sensible of yet helpless in the face of) are the insignificant lives we live in between eating and drinking.

... Competence with pain,
coherent miseries, a bite and sup,
we hug our little destiny again.

These lives, that we hug to ourselves dearly for all their insignificance, are contrasted to the lives of internees that are carried on just at the edge of our daily commutes. The nearness of such strangeness gives a movie-like effect to our glimpses of these counter-realities, these separate lives that we glimpse from the "motorway" as we drive by in the early, dew-covered morning under "white mist" on a "low ground."

white mist you get on a low ground
and it was déjà-vu, some film made
of Stalag 17, a bad dream with no sound.

In the distance, seen as we pass, are the gun rests of a pillared stockade that corrals the internees and tames them into quietude and submission. The crater of a fallen bomb gapes in "the fresh clay in the roadside" reminding us as we drive by (as though in a dream or a moment of "déjà-vu") of the reason for the "new camp for the internees"; of who the internees are; and of what "machine-gun posts" are for ...

machine-gun posts defined a real stockade.
[stockade: enclosure formed from upright wooden posts as a defense against attack or a means of confining.]

This deeply personal and introspective poem is a heartbreak of a witness to the conflict between daily, productive life and a conflict-torn life guarded by a stockade. It is dedicated to David Hammond, Heaney's long-time friend and noted filmmaker, and Michael Longley, a fellow Northern Irish poet of notable reputation himself and an equally long-time friend. Heaney, Hammond and Longley published a book of collected poems together called Ten Poems put out by Festival Publications in 1965.