Considering Spartans were born and raised as warriors there would be no shortage of man power. Warfare was in their blood, every warrior knew tactics again kind of nullifying the tactic of disrupting their communicatiom in terms of no tactics

Although my knowleadge is limited i cant think of a way of defeating the Spartans without a massive advtanage in terms of war technology (stronger armour. Weapons that can pierce any armour etc.) or by sheer numbers