Tug of war

The sport of tug of war has shown up in old Egyptian paintings where they didn't use rope but instead held hands and pulled toward each other. At some point rope was introduced. When it became a figurative phrase that meant a play for power/authority is a little unclear but this phrase showed up in 1713 in Ovid's Tristia, "His Nerves could all the Tug of War sustain, My brittle Limbs submit to Toil and Pain" and it is not referring to the sport of tug of war. So it seems a figurative use of the phrase began around that time. (source)