What is another historical event that could fit into the poem "Five ways to kill a man" ?
If I understand you correctly, you want another historical event that would sort of go with the theme of this poem, is that right?
There are two themes that I see in this poem. The first seems to be that senseless violence is well, senseless. The second is that the middle of the 20th century was, in his opinion, a bad time to be alive.
I assume what you are looking for is another episode of what Brock might think was senseless violence. There are many possibilities. Perhaps the most obvious one would be the Crusades. I think he would say they fit perfectly with the kinds of things he's talking about -- horrors which were caused by human cruelty and which had no real purpose.
Another possibility would be the way the British put down the Sepoy Rebellion in India. Or maybe American wars against the Indians. No shortage of historical episodes that show people being nasty...
If you are looking for a post-World War 2 historical event that fits well into Edwin Brock's poem and that goes along with its themes and style, I would suggest the genocide in Rwanda in the 90s or the continuing genocide in Sudan.
You could also discuss the assassination of one person, because the 50s and 60s contain themurders of Malcolm X, Martin Luther King Jr., and JFK.
Since the stanzas of the poem are in chronological order, I think that it would be best to choose an event that is after the bombing of Hiroshima and Nagasaki (described in the fourth stanza) and possibly one that is not war-related since stanzas 3 and 4 discuss that topic.