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.
At 80 letters, the longest word ever composed in German is DonaudampfschifffahrtselektrizitÃ¤tenhauptbetriebswerkbauunterbeamtengesellschaft, the Association for Subordinate Officials of the Head Office Management of the Danube Steamboat Electrical Services.