Marlow's tale of ancient England introduces the types of characters that are encountered later in his story of Africa. First, Conrad mentions the Roman who comes to England simply "to mend his fortune" (6). Later, Marlow's portly companion on his 200-mile trek to the Manager's African outpost is introduced into Marlow's story with the identical characterization, "to make money" (20). However, more importantly, Marlow tells of the Romans who had come to England "to face the darkness. And perhaps he was cheered by keeping his eye on a chance of promotion to the fleet at Ravenna" (6). Here Conrad first foreshadows the character of Kurtz through this description of the upward-looking, ambitious Roman adventurers. Kurtz is described to Marlow by the brick maker as being "chief of the best station, next year he will be Assistant-Manager, two year's more and… but I dare say you know what he will be in two years' time" (25). Kurtz, like the Romans, is ambitious and on a straight track to a more prominent position in the Belgian company which employs him. Another element of the character of Kurtz is referred to in Marlow's story of the Romans coming to England as Marlow cites "the fascination …[and] the hate" (6) that develops inside the Roman conqueror. This attitude is a direct foreshadowing of Kurtz and how throughout the novel "he hated [Africa] and somehow he couldn't get away"(56). Marlow suggests that the Romans and Kurtz were fascinated with the primal scene despite their hatred for what they found. Marlow, in his story of the Romans coming to England, introduces the types of personalities drawn to conquests, all of which are negative. He sees Roman and Belgian colonization drawing the egotistical, who do not come for noble purposes such as nationalism or for the betterment and education of the natives, but rather are drawn for the opportunity for self-advancement.
Conrad uses the tale of the Romans in the frame story to foreshadow the plot that unfolds as these self-centered Roman and Belgian characters begin to experience and react to the "new" world that they have found. First, he relates the situation of the Romans as they penetrate the primordial landscape, finding "sandbanks, marshes, forests, savages, precious little to eat fit for a civilized man, nothing but Thames water to drink" (6). Marlow foreshadows the future story of the conquerors of Africa, as later the Belgians and Marlow will find the same "primeval mud" (26) in their journey into Africa. Conrad implies that neither the Romans nor the Belgians adapt and accept the new landscape and feel that it is unworthy of a sophisticated man. Marlow goes on to call the Romans not "colonists" (6), but rather "conquerors…They grabbed what they could get for the sake of what was to be got. It was just robbery with violence, aggravated murder on a great scale" (7). Marlow foretells of the injustices to the natives that the Belgians will commit once they have conquered Africa. By expanding on his description of Romans, Marlow also foreshadows Kurtz's fate. He says that a Roman will only have success "if he… survived the awful climate"(6). Marlow's words are a presage of Kurtz's death due to an indigenous African disease. Marlow thus says that the type of colonization practiced by the Romans and Belgians will ultimately end in failure. Conrad then uses this foreshadowing of characters and plot to foretell the theme of his novella.
Joseph Conrad, like Marlow, had taken a voyage down the Congo viewing malevolent colonialism first-hand; thus Conrad speaks directly through Marlow. Marlow, and therefore Conrad, decries colonialism as was practiced by the Romans. This opinion of the Roman invasion of England is a foreshadowing of his feeling of the Belgian colonization of Africa. Therefore, Conrad is also condemning Belgian colonialism, implying that all humans have a capability for the immoral brutality associated with colonization. He then uses this idea to imply that the cruelty in modern day imperialism is not a product of the Industrial Revolution, and rather has been around for centuries. Conrad then attempts to separate Roman and Belgian imperialism from British imperialism. Marlow says when speaking to his British friends about Roman colonization, "mind, none of us would feel exactly like this" (6). Using the term "us" (6), he implies that the British would react better than the Romans and Belgians had in a similar situation. Marlow's pro-British sentiments are voiced once again in the story of his trip to Africa. When preparing to leave for Africa, he sees a map detailing colonization efforts on that continent. Upon seeing the red symbolizing British territory he says, "there was a vast amount of red - good to see at any time because one knows that some real work is done in there" (10). Conrad, through Marlow, sees English colonization as the righteous form of colonialism. Thus, Conrad vindicates modern English imperialism as more acceptable than inhumane Roman and Belgian imperialism.