Three riders, the poem's narrator amongst them, ride their horses at top speed from the town of Ghent, on their way to Aix to deliver important news for the latter town's survival. The nature of the news is never revealed in the poem. The riders do not speak to each other on their intense journey but instead are focused on keeping their steeds at top gallop. They ride through the night, passing towns which the narrator marks solely by the movement of the day and night in relation to them. At Aerschot, the sun rises again and the narrator notices the cattle watching their gallop. He also refocuses on keeping his own horse, Roland, at top efficiency.
Near Hasselt, one of the riders, Dirck, is left behind when his horse dies and unseats him. The third rider, Joris, insists they continue onwards, and they do until they finally see Aix in the distance. At this moment, Joris's horse also dies and it is left to the narrator and Roland to carry the news onwards.
The narrator rids himself of his guns and some of his clothing to lessen the weight, and they make it into Aix. There, they are surrounded by gracious citizens while the narrator sits with Roland's head between his knees. The town gladly allows Roland to drink their "last measure of wine" in thanks for having carried the news.
This poem, published in 1838, tells of an entirely fictional trip to bring news, presumably of defensive value, from one ally to another. Its story details are far less important than the sense of movement and sacrifice that permeate the poem.
The narrator of the poem is noticeably flat in his characterization, a trait which we would not expect from Browning. And yet this missing element only reinforces the poem's primary theme: sacrifice. The riders are entirely devoted to their mission, and everything in the poem is viewed in service of that mission. For example, the many cities and towns that the narrator mentions are described solely in terms of how they mark the passage of time: "At Boom, a great yellow star came out to see"; Duffeld is associated with the rise of morning; and so on. Another example is in the penultimate stanza, when the narrator begins to drop his clothing and accessories to lessen the weight. He is literally making himself naked before the mission, as though to say that the rider himself is less important than the goal he is duty-bound to reach. The stakes are high and time is of the essence, so the narrator does not allow himself license to characterize anything except for the mission itself.
The one exception to this is his characterization of his horse, Roland. Other than the anxiety that permeates the ride, the only emotion he shows is a subtle admiration of the horse's dedication. Roland's "resolute shoulders," the "black intelligence" of his eye, and his "fierce lips" all distinguish his strength in a way that justifies the celebration that closes the poem. It is telling that the poem, which begins focused on the mission, does not end with a celebration of the mission's completion, but rather with a celebration of the horse's sacrifice. The rider and his horse fulfill this mission, it seems, as a matter of duty, so that once complete, the narrator can focus again on the human (albeit in a horse) quality of sacrifice. That both the other horses fall on the trip further validates the stakes of the speed and intensity that make Roland the poem's hero.
The most effective means of delivering these themes of sacrifice and movement is also the poem's most defining characteristic: its rhyme scheme. Browning claims he wrote the poem to try to capture the sound and rhythm of galloping horses, and one can sense how the poem begs to be read quickly yet methodically, all in all suggesting the sense of anxious movement that characterizes the sacrifice that Roland and the speaker make. It is a mixed meter, which uses both an iamb and amphibrachs (which put a stressed syllable around two unstressed syllables); this meter captures in each line the up-down-up rhythm one associates with a horse's gallop.