fans have branded the period drama "unwatchable" after it returned for the second series on Sunday (January 12).

The seven-part series - based on the book of the same name written by Ben Macintyre - follows the lives of the Special Air Service (SAS) and its role in World War II. In the first series, set in 1941, British forces are losing ground in North Africa to the German Afrika Korps.

Three British Lieutenants - David Stirling [played by Connor Swindells], Jock Lewes [Alfie Allen], and Paddy Mayne [Jack O'Connell], come up with the idea to dorm an elite parachute regiment to attack German supply depots and airfields.

In the second series, viewers watch the regiment make waves over Nazi-occupied Europe. David Stirling is captured and now a prisoner of war. His brother Bill Stirling and Paddy Mayne are forced to work together to save the SAS.

Bill Stirling wants to rally Mayne to lead the reorganised SAS, but Mayne is described as "an Irishman of poor temperament" who is unhappy with authority.

The first episode of the new series explored the devastating attack in Termoli which took place from October 3 to October 5, 1943.

Thankfully, entire 16th Panzer Division was held at bay long enough for relief to arrive and save the Italian fishing town, but 21 members of the SAS/SRS died in the battle.

However, many viewers were disappointed with the new instalment of the period drama after spotting one annoying habit on the show. One user penned: "Paddy Mayne's accent and syntax is increasingly grating #sasrogueheroes."

Another agreed: "Why the hell did @bbctvcentre make Paddy Mayne seem like such a t**t in #SASRogueHeroes? Literally s***s on the legacy of the man."

A third chimed in with: "Every time 'Paddy Mayne' opens his mouth, I cringe. It has destroyed the whole thing #sasrogueheroes."

Meanwhile, others simply struggled to stay interested in the show, One user wrote: "Dreadful season 2. Fantastic machismo which totally disgraces the ethos of the regiment. Soundtracked by noise and drum bashing discredits. Get a bloody grip @BBC #SASRogueHeroes."

Another added: "Thought the first series of #sasrogueheroes was cr*p. Season 2 seems equally b******s. Glad I've missed it [yawning emoji]." However, many fans raved about the grisly episode and couldn't wait to watch more next week.

One user posted: "Fantastic episode tonight #SASRogueHeores" as another agreed: "Over the years, there have been very few TV shows I've looked forward to watching, but #SASRogueHeroes is one of them. I adore this show."

A third pondered: "I know that #SASRogueHeroes is a war series but this 2nd series doesn't pull any punches. War is hideous. No wonder people come back from it changed."

SAS Rogue Heroes airs on Sundays from 9pm on BBC One or catch up on BBC iPlayer.