Though her clearance papers were in order, word had arrived to at Fort Queenscliff that England had just declared war on Germany, and the ship was ordered to stop.

When she didn’t, a gun crew at Point Nepean fired a shell across her bow, and the first shot fired by the British Empire in World War I sank to the bottom of the bay.

A century later, wreck hunters led by Mark Ryan of Southern Ocean Exploration are trying to find that shell, and have begun surveying the seabed in an effort to locate and recover the historic artifact. They call it Project Longshot.

“Generally we are looking for 500-tonne ships,” Mr Ryan said. “This is a 40-kilogram shell, so to find something so small is quite a challenge.”

The group began their research with historian Keith Quinton, a Pfalz expert who spent five years studying the events of that day. Together, they pored over the records and came up with a plan.

“We know it was fired between 12:30 and 12:45,” he said. “We’ve been able to figure out the angle it was fired at and we’ve more or less got the distance. All those things have been pinned down.”

The team intends to search an area covering one square kilometre located about four kilometres north-east of Point Nepean. If nothing is found, the search zone will be expanded incrementally to a maximum area of 10 square kilometres.

The challenges are many. They can only search in good weather and the currents are strong near the heads of the bay. Mr Ryan said the shell was likely to be buried more than a metre under the sand and “won’t be found by swimming around on the bottom with a couple of divers”.

To find such a small object, the team has determined it needs a specialist piece of equipment called a transverse magnetometer. When towed behind a boat, it can detect minute fluctuations in the earth’s magnetic field caused by the presence of metal.

On Friday the team officially launches its Longshot crowdfunding campaign, where they hope to raise the $85,000 needed to buy a magnetometer. Without it, Mr Ryan said it was unlikely the project could proceed.

“We knew it was going to be a tough assignment when we took it on,” he said. “But I believe we have the team dedicated enough to see the project through.”

Mr Quinton called the firing of the shell “a momentous event in a great war”, and said finding it would be incredible.

“It was the first British Empire moment in a war that took hundreds of thousands of lives, so it has significance,'' he said.

The SOE team hopes to have located the shell in time to mark the war’s centenary on August 5, but has vowed to keep looking well beyond that date if necessary.

“The ANZACS are are a great part of Australian and New Zealand history,” says Mr Ryan, whose grandfathers both fought in the war.

“I think it defines who we are. To actually find the shell would be amazing. It’s a story of such interest, not only to us, but to the whole world.”