On a thousand small town New England greens, the old white churches hold their air of sparse, sincere rebellion; frayed flags
Picture a movie screen panning out. This is what we're looking at now. Instead of focusing on the memorial site at the center of Boston, we're looking out over all of New England.
Rebellion means to resistance to authority. What is this attitude of rebellion exactly? Well, it's probably related to the founding attitude of New England, breaking away from the rule of England's monarchy.
The "frayed flags" at the end of line 39 are American flags, and they are a particularly meaningful symbol for the Union—remember the union fought for the Republic, for all states to be one nation.
Although Lowell has done a good job painting a picture of good old-fashioned New England rebellion and patriotism, he's also snuck the words "sparse" and "frayed" in there which alters the scene somewhat.
"Sparse" means thinly dispersed or scattered. That might mean that although evidence of the rebellious spirit of the Civil War era is still in evidence, it's dwindling.
That the flags are frayed has a similar effect on the spirit of rebellion and patriotism. It's coming apart. Think about this in the larger context of what we've already read. Colonel Shaw and his infantry's statue is sitting in the heart of Boston being shaken violently by construction, and it's protected by a single, flimsy plank. The old flags are frayed. Maybe Lowell is trying to point out that approaching the height of the Civil Rights era (when this poem takes place), people are beginning to forget the importance of the Civil War and its role in the present-day struggles.
quilt the graveyards of the Grand Army of the Republic.
The American flags are scattered like quilt squares all over the graveyards of the Union soldiers in New England.
Quilts are quintessential Americana. So flags + quilts = super-American!
This large, panoramic shot of patriotism and commemoration for those that died for the Republic illustrates how much respect the New Englanders gave to the Union soldiers of the Civil War. Is Lowell's tone of criticism fading?