In July 2019 and the oil tanker Grace 1 was seized by the Royal Marines in support of the Gibraltar government on suspicion of breaking sanctions against Syria.
Tensions in the region escalated rapidly after Iran retaliates, attempting to intercept oil tanker British Heritage, and later seizing the British-flagged tanker Stena Impero.
Ther Navy was called in to help protect shipping in the Strait of Hormuz, a narrow channel between the Persian Gulf and the Gulf of Oman.
"The Iranian government made a direct threat to British-flagged merchant vessels transiting through the Strait of Hormuz and the Arabian Gulf," Commodore Dean Bassett, UK Maritime Component Commander, said.
"This threat was taken very seriously by the British Government and therefore by the Royal Navy.
"The Royal Navy was tasked with the protection of those British-flagged merchant vessels [that] transit through the region."
The UK Maritime Commander in the Middle East needed someone who could integrate all the available data to create a detailed picture of shipping movements in the area.
He called on reservist Lieutenant Commander Tracy MacSephney, a maritime trade operations specialist.
"Part of my reserve job at the moment is delivering maritime trade operations training to the other reserves because it's very much a niche capability that is only provided by the reserves - the regulars don't do this at all," Lieutenant Commander MacSephney said.
"The ability for Tracy to turn up out here [at UKMCC Bahrain] at a moment's notice, transition from her civilian job into a highly stressful environment of a naval operation headquarters when there was a direct threat to shipping in the region and turn her attention to operations at a moment's notice clearly lays her out as a hugely professional and dedicated individual," Commodore Bassett said.
"Trying to understand who has an interest in what ship is incredibly difficult," Lieutenant Commander MacSephney explained.
"You're talking about who owns the ship, where the ship is registered, who owns the cargo, who supplied the cargo, who is buying the cargo... all of that feeds into this global shipping industry and it's massive."
Middle East Defence Consultant Commander (Ret’d) Tom Sharpe OBE said the Navy and the Merchant Marine operate in "different spheres".
"Having someone with experience of both, who can drop everything they're doing, fly abroad and tackle this situation in a rapidly-developing scenario is very difficult," Commander Sharpe said.
Commodore Bassett added: "Without Tracy being here I would not have had the picture I needed to position my ships according to the threat."
For her efforts, Lieutenant Commander Tracy MacSephney won the 2019 'Best Reservist' at The Sun Military Awards.
Watch extended highlights of the Millies on Wednesday 12 February at 18:30 UK time on Forces TV, and at 19:10 UK time on BFBS Extra.