Most Impressive Fighting Force (In Your Opinion)

[HMS Empire Broadsword]

What, in your opinion, is or was the most impressive/elite/sucsessful fighting unit?

Not major things like the US Army or the Royal Navy, but individuals such as;

Ships, (Yamato, HMS Victory, Santistima Trinidad, HMS Warrior etc)

Regiments (Roman Xth Legion, 42nd Black Watch, Grenadier Guards, 501st Us Airbourne, Panzer Lehr)

Or "special" things (Spartan "kings bodygaurd", SAS, US Delta Force, Spanish Guerillas)

Or even individual people (http://en.wikipedia.org/wiki/Jack_Churchill)

[Elzabar]

The same type of thread was recently closed here. Reasoning:

"Best xxx ever" does not become a VV thread by adding the suffix "in history". Threads of that kind belong in the Thema Devia, not the Vestigia Vetustatis.

Please post in the Thema Devia if you would like to discuss this topic. Cheers.

- Elzabar