Pausanias Description of Greece 1.32.3

[3]
  Before turning to a description of the islands, I must again proceed with my account of the parishes. There is a parish called Marathon, equally distant from Athens and Carystus in Euboea . It was at this point
  in Attica that the foreigners landed, were defeated in battle, and lost some of their vessels as they were putting off from the land. ¹ On the plain is the grave of the Athenians, and upon it are slabs giving the names of the killed according to their tribes; and there is another grave for the Boeotian Plataeans and for the slaves, for slaves fought then for the first time by the side of their masters.

[3] Before turning to a description of the islands, I follow up further on matters having to do with the demes [ dēmoi] [of Attica]. There is a deme [ dēmos] called Marathon, equally distant from the city [ polis] of the Athenians and from Karystos in Euboea. It was at this point in Attica that the barbarians landed, were defeated [ krateîsthai] in battle, and lost some of their ships as they were trying to pull away [from the shore]. 130

On the plain [ pedíon] is the tomb [ taphos] of the Athenians, and upon it are slabs [ stēlai] with [inscriptions of] the names of those killed, organized by way of their subdivisions [ phūlai]; and there is another tomb for the men of Plataea from Boeotia and also for the slaves. I say-this-because [ gar] slaves too fought there, and it was the first time that this happened.