Battle of Thunder Plain

The Battle of Thunder Plain was not recorded by the Unicorn and it was considered a tactical error.

Preamble
For unknown reasons hostilities were brewing between the Iuchi and Kaiu families. The Iuchi Daimyo decided to settle the matter with a single, swift decisive attack on a Kaiu village, and their path would cross the Plain of Thunder.

Battle
The sohei of the Order of Osano-Wo did not to let the sacred Plain be soiled by the war-mongers, so the Iuchi forces were attacked brutally, using polearms against the Unicorn cavalry. When the Iuchi turned their magic to defense, the kami did not respond, and retreated to Unicorn lands after a sound defeat.

Aftermath
Since this event, relations between the sohei and the Unicorn had been strained, but the Iuchi had sought no retribution.