Bierce shares with Stephen Crane the soldier’s appreciation for an essential truth of battle—that things rarely are what they seem. In the first example, the woods that the narrator's platoon scouts appear to be quiet, but suddenly seem to “disappear with a crash like that of a great wave upon the beach.” Shooting breaks out, and, with the “sickening ‘spat’ of lead against flesh,” a dozen of his soldiers are killed in an instant. Your question about the ”limits of language” refers, I think, to this difference between appearance and reality, or to the notion that the hidden “reality” of battle—the instant in which the woods become a killing field—can’t be fully captured in words. Bierce nevertheless uses some potent sensory details here: not just the sound of lead hitting bodies (“spat” is a disturbing, almost comical way of describing it), but also the “little jet of mud” caused by bullets hitting the ground. These descriptions are visceral but also incomplete. This incompleteness is characteristically emphasized by the “ludicrous” understatement of the officer’s report that the enemy is “just beyond this field.”
The same dynamic is at work in the second example. The exclamation “Faugh!” does suggest impatience on the part of the narrator at the inadequacy of words to explain the horrors of the ravine, but he then goes on to render some gruesome details, nevertheless, like describing the bodies “half buried in ashes,” clothing and hair burned away, facial muscles contracted into “hideous grins.” Once again, Bierce acknowledges the inadequacy of his description with a kind of bitter irony: “I cannot catalogue the charms of these gallant gentlemen who had got what they enlisted for.”
The final example perhaps best demonstrates the strangeness of war. The child’s surreal experience in the forest, his encounter with the crawling soldiers, and his final recognition that his home is burning, are in part “explained” by his being a deaf mute, but his lack of hearing and speech underlines the narrator’s own inability to express what has happened to him in real terms. The final image—of the woman, her skull broken like a shell—is shocking in its graphic nature but also in its incompleteness: is this his mother? The child’s inarticulate cry is described as “the language of the devil.” Perhaps such a language is needed for the atrocities of war.