4. The Napoleonic Wars: 1803-1815
The Doctor has met Napoleon a few times, and he's apparently friends with Admiral Nelson. What more do you want? The Napoleonic wars can include great set pieces like Trafalgar or Waterloo, and great characters like the aforementioned Nelson and the Duke of Wellington (bonus points if played by Stephen Fry). But it's the sea battles where there is some really good material to be gleamed from this period. Aside from 'The Curse of the Black Spot' which didn't really explore its main setting we haven't really had a true nautical Who adventure. I mean a proper, on the high sea, Master and Commander-style story about a Captain and his crew. It could even be aboard the HMS Victory. The Doctor having tea with Nelson making bad jokes about eyes and arms, anyone?