a long chain of ships; a vast fleet stretching far
A classical four-character idiom (yojijukugo) describing a great number of ships sailing in a line that extends for a thousand leagues. Used in literary or historical contexts.
The phrase 舳艫千里 was used to describe ancient naval battles or large fleets.
From Chinese classical literature; 舳 (じく) means 'stern', 艫 (ろ) means 'bow', and 千里 (せんり) means 'a thousand leagues', together evoking an unbroken line of ships stretching into the distance.