Hull played into a strong wind in the first half and outscored the visitors by two tries to nil. Chris Murphy opened the scoring after his brother Phil won a line-out five metres from Ionians' line to give Hull a 5-3 lead after 20 minutes.
Five minutes later, another close-range line-out paid dividends when Chris Murphy rose to win possession for Byron Godfrey to score the first of his two tries, but three penalties in the closing stages of the first half saw Ionians turn around 12-10 in front.
For the majority of the second half, both sides found points hard to come by. Ionians failed to score against 14 men after Rhun Jones' sin-binning for his tackle on Bateman early in the second half.
Hull's indiscipline got worse and they conceded 10 of the 12 penalties awarded in the second half, although Ionians struggled to turn them into points.
With seven minutes remaining Ionians Captain, Joe Makin, took a five-metre line-out from which prop Ben Harris went over from close range. Marshall missed the conversion leaving a converted try between them .
Hull were up against the clock and a spirited Ionians side. They stepped up a gear and within minutes they were knocking on Ionians door.
Finally it opened for Godfrey to score his second of the game.
All eyes were on Cameron's conversion. Kick it and the sides were level. Miss it and Ionians only had to run the clock down.
On their second half performance, Hull would have taken two points on offer but Cameron's decision to chip inside his own '22' backfired as Ionians mounted one final assault. Centre Ollie Marns waltzed through the Hull defence before play was spread wide to the right for full-back Bateman to score and Marshall kicked his fifth goal from seven attempts.