Could I have an explanation of the poem "Channel Firing?"

Channel Firing, by Thomas Hardy (1840-1928) is a dialogue among the dead who are awakened by the naval "great guns" firing artillery in the English Channel. The central theme of the poem suggests that warfare has gotten so destructive that  Armageddon, the final battle at the end of the world, is at hand, and the dead are awakened for Judgment Day. God reassures them that no, it's just the living engaging in "redder" warfare; a skeleton that used to be the parson states that his lifetime would have been better spent enjoying himself  ("I wish I had stuck to pipes and beer,") rather than preaching, since apparently it had had no positive effect on the subsequent generations. The last stanza suggests the enemy's "return fire" with shells landing far inland. What's interesting is that Hardy was writing about the First World War, but the intensity of the destruction he conveys in his poem more accurately describes the destruction during and at the conclusion of World War II, when the most destructive weapon of all was set upon the world.