The speaker of "A Far Cry From Africa" uses a lot of metaphorical language, and some of this is framed explicitly through simile.
Line 2, for example, introduces a striking comparison:
[...] Kikuyu, quick as flies,
Batten upon the bloodstreams of the veldt.
The Kikuyu are the tribe that composed most of the Mau Mau. Here, the speaker compares the Kikuyu—probably thinking specifically of the Mau Mau—to flies that fasten to bloodstreams (i.e., veins). They are like mosquitoes or flies pecking at a body. This is a bold and ambiguous comparison to use right off the bat, especially for this speaker who is sympathetic to the project of African independence. The simile suggests the Kikuyu are like parasites or scavengers. Although the speaker has African ancestry, clearly the actions of Mau Mau have left the speaker unsure how to feel about them.
At the end of the first stanza, the speaker references "savages, expendable as Jews." Here, the speaker parrots the racist ideologies of colonists and Nazis. Colonists have often referred to colonized natives as "savages," uncivilized people who needed to be ruled by Christian colonists; the Nazis killed millions of Jewish people in concentration camps in an effort to exterminate them. In comparing these two ideologies, the speaker suggests that colonists are no better than Nazis. If the comparison of the Kikuyu to flies has a queasy ambiguity to it, there's no question about where the speaker stands on colonists—they are reprehensible.
In the second stanza, the speaker says that "man" is "Delirious as these worried beasts." In other words, people who engage in acts of violence as just as crazed as predator and prey locked in a battle for survival. Although people often like to think of themselves as above animals, the speaker implies that this belief is refuted by humans' use of violence. In their thirst for blood, according to the speaker, British forces and Kenyan rebels are no different from hunger-crazed lions.
And in the third stanza, the speaker says that the Mau Mau rebellion is "A waste of our compassion, as with Spain." Here, the speaker compares the Mau Mau rebellion to the Spanish Civil War, fought in the 1930s between left-wing and right-wing Spanish forces. Despite vicious fighting, leftists lost that war and a totalitarian government rule Spain for four decades. According to the speaker, the Mau Mau rebellion, like Spanish civil war, isn't worth the sympathy of liberal people. Not only do the Mau Mau use tactics the speaker disapproves of, but they will also probably lose to the larger and better-armed British army.