A mistake, however, was made in the days on which they were each to start; and Demosthenes, sailing first to Siphae, with the Acarnanians and many of the allies from those parts on board, failed to effect anything, through the plot having been betrayed by Nicomachus, a Phocian from Phanotis, who told the Lacedaemonians, and they the Boeotians.

Succours accordingly flocked in from all parts of Boeotia, Hippocrates not being yet there to make his diversion, and Siphae and Chaeronea were promptly secured, and the conspirators, informed of the mistake, did not venture on any movement in the towns.
Meanwhile Hippocrates made a levy in mass of the citizens, resident aliens, and foreigners in Athens, and arrived at his destination after the Boeotians had already come back from Siphae, and encamping his army began to fortify Delium, the sanctuary of Apollo, in the following manner.

A trench was dug all round the temple and the consecrated ground, and the earth thrown up from the excavation was made to do duty as a wall, in which stakes were also planted, the vines round the sanctuary being cut down and thrown in, together with stones and bricks pulled down from the houses near; every means, in short, being used to run up the rampart.

Wooden towers were also erected where they were wanted, and where there was no part of the temple buildings left standing, as on the side where the gallery once existing had fallen in.
The work was begun on the third day after leaving home, and continued during the fourth, and till dinnertime on the fifth, when most of it being now finished the army removed from Delium about a mile and a quarter on its way home.

From this point most of the light troops went straight on, while the heavy infantry halted and remained where they were; Hippocrates having stayed behind at Delium to arrange the posts, and to give directions for the completion of such part of the outworks as had been left unfinished.
During the days thus employed the Boeotians were mustering at Tanagra, and by the time that they had come in from all the towns, found the Athenians already on their way home.