Oda Nobunaga set out under cover of night, racing toward the front line. By the time daylight broke, there were no longer just a handful of people behind him—numerous Oda Family household retainers and powerful conscripted clansmen had caught up on horseback. They had no choice but to chase; if they really let Oda Nobunaga head out alone, they'd lose face for good, let alone risk having old grudges come back to haunt them in the future.
At the very least, they had to catch up and see what was going on, to figure out what exactly had happened.
However, because Oda Nobunaga had set out so suddenly, none of these men were prepared. Though they'd caught up, they were commanders without troops—aside from a few personal attendants, they had neither soldiers nor followers with them.