As the excerpt is not provided I looked it up and here is the excerpt:
"O Captain, my Captain! Our fearful trip is done;
The ship has weathered every rack, the prize we sought is won."
- Walt Whitman, 1865
The answer is “Civil War”.
The fearful trip in this refers to the horrors and frights of Civil War. The author utilized a figure of speech to highlight the suffering and experiences during that war. It is reported that the poem was a dedication to Abraham Lincoln after his demise.