Since the latter part of the 19th century the duties of cruisers, although many and varied, have been reasonably well defined. The design of the ships themselves, however, constantly fluctuated depending upon the naval policy of the period and until 1914 the policy on cruiser design was seriously hampered by lack of war experience. By the 1890 s cruisers had developed into 1st, 2nd. and 3rd class protected cruisers designed for commerce protection. In 1899 the armoured cruiser was reintroduced and from this type the battlecruiser was evolved. The Invincible Class battlecruisers were among the most controversial warships ever built. The brainchild of Lord Fisher, they were the first battlecruisers to be built, and the fastest capital ships in existence. With the speed of a cruiser and the gunpower of a Dreadnought, the Invincible Class was calculated to overpower any weaker ships and to be able to escape from anything stronger.Unfortunately, the lack of protection proved their undoing, and in battle the battlecruiser proved very vulnerable. In 1914 the Invincible Class proved deadly in action against cruisers, when they sank the German Scharnhorst and Gneisenau at the Battle of the Falklands. But, when faced by capital ships at Jutland their weaknesses were revealed. Invincible blew up with the loss of more than 1,000 men, and two other battle cruisers were similarly lost.