 The Lion class were a class of battlecruisers built for the British Royal Navy before World War I. Nicknamed the " Splendid Cats " , the ships were a significant improvement over their predecessors of the Indefatigable class in terms of speed , armament and armour . The Lion @-@ class battlecruisers were 2 knots ( 3 @.@ 7 km / h ; 2 @.@ 3 mph ) faster , exchanged the 12 @-@ inch ( 305 mm ) guns of the older ships for 13 @.@ 5 @-@ inch ( 343 mm ) guns , and had a waterline armour belt 9 inches ( 229 mm ) thick versus the 6 inches ( 152 mm ) of the Indefatigables . These improvements were in response to the German Moltke class , the first German battlecruisers , which were larger and more powerful than the first British battlecruisers of the Invincible class . 
