 Since time was passing and the Mantinean alliance showed no signs of capsizing, Epaminondas decided that he would have to break the stalemate.Hearing that a large Lacedaemonian force was marching to Mantinea, and that Sparta was practically undefended, he planned an audacious night-time march on Sparta itself.However, the Spartan king Archidamus was alerted to this move by an informant, probably a Cretan runner, and Epaminondas arrived to find the city well-defended.