That one time everbody thought ships ramming other ships was a great idea
And I'm not talking about the ancient world, either. No, in the mid-19th century navies of the world went gaga with the idea of attaching rams to their new iron-hulled, steam-powered warships. Largely this was because of the CSS Virginia and the Battle of Hampton Roads, where the ironclad successfully sank the USS Cumberland after ramming her. This idea was further reinforced after the Battle of Lissa, which had so much ramming, you'd think it was a gay porn shoot.
CSS Virginia ramming the USS Cumberland.
The single biggest reason for the reintroduction of ramming, however, was technology. Armor had outpaced gunnery and as a result, ship mounted cannons of the day couldn't penetrate the hulls of ironclads. So combine the three and everybody went "Well clearly ramming the hell out of the other guy is the way to go!" and so you have countries building battleships and cruisers with those things. Ironically, these rams were effective...at sinking friendly ships whenever one accidentally collided with another.
There was even a variation: the torpedo ram. These ships combined rams with torpedoes - first as a combined
weapon and later as two separate entities - because once people get
attached to an idea, they're going to ride it all the way home, no
matter how ill-thought out it is.
Fortunately, naval gunnery eventually caught up and the idea of ships ramming other ships quietly faded away. Mostly. Torpedo rams were immortalized by H.G. Wells in War of the Worlds when the HMS Thunderchild, a torpedo ram battled and destroyed two Martian walkers.
Gotta love mid-to-late 19th century naval warfare and its awkward, puberty like growth.