The Peloponnesian war was between the empire established by Athens out of the cities which allied to repel the Persians, and a Peloponnesian League headed by Sparta which opposed Athens when it transferred its attentions to its Greek neighbours.
The longest word in any of the major English language dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis, a word that refers to a lung disease contracted from the inhalation of very fine silica particles, specifically from a volcano; medically, it is the same as silicosis.
(29) FLOCCIÂ­NAUCINIÂ­HILIPILÂ­IFICATION = an estimation of something as worthless. This is the longest word in the first edition of the Oxford English Dictionary. Interestingly the most common letter in English, E, does not appear in this word at all, whilst I occurs a total of nine times. The word dates back to 1741.