Possible Clues:

• Pool sport
• Olympic team game with a goalkeeper
• Washington's international force not in Oman at first for aquatic exercise?
• Net game
• Game featuring seven-person teams (2 words)
• Confounded tar we found before swimming pool game
• Team sport with wet participants
• 'Battle' almost describes potty game
• In a way, Napoleon's defeat here around Paris initially, leads to game played out in water
• Aquatic sport's endless battle round river