What distinguished the ships of the line during the 19th century?

The ships of the line during the 19th century were primarily distinguished by their size and firepower. These ships were designed to be the backbone of naval fleets, heavily armed with numerous cannons arranged on two or more decks, allowing for devastating broadsides in naval engagements. The considerable size of these vessels, combined with their armament, made them formidable opponents and essential for fleet actions.

The function of a ship of the line was to engage in the line-of-battle tactics that dominated naval warfare of the time, where fleets would form a line to maximize their broadside fire against the enemy. This larger size also typically allowed for more robust hulls, which were necessary to withstand the heavy fire sustaining engagements.

While speed and maneuverability, as well as unique designs like keels, were considerations in naval design, they were not the primary distinguishing features for ships of the line compared to their contemporaries. The emphasis on carrying aircraft, such as in modern naval vessels, was not applicable during the 19th century, as this technology did not exist at that time.