The Stoke City player has replied to the men booing him at the weekend.
The 29-year-old, who began his career at his local side Derry City, has attracted controversy over the years for taking the same decision at previous clubs Sunderland, Wigan and West Brom.
Despite Stoke City confirming they will be supporting the Royal British Legion's Poppy Appeal by wearing embroidered poppies on their shirts against Middlesbrough on November 3 and Nottingham Forest on November 10, there is no enforcement of each player to wear the poppy.
Stoke City said they "respect his decision and his right to follow his own convictions".
A club spokesperson said: "The club is proud of its close connections with the armed forces and have also invited members of the armed forces to join our remembrance at the Middlesbrough fixture.
"However, we recognise that the poppy means different things to different individuals and communities and (like the Royal British Legion) do not believe that anybody should be forced or even pressured to wear the poppy against their free will."
Replying to critics of his decision to not wear the poppy, the midfielder took to Instagram to quote hunger striker Bobby Sands and reassured the public of his Fenian stance:“They have nothing in their whole imperial arsenal that can break the spirit of one Irishman who doesn’t want to be broken.” Your abuse, your throwing things, your booing, do your worst.. to the home fans that are actually educated and support me, thank yous..
"To the section of uneducated cavemen in left hand corner of the boothen end stand that want to song their anti irish song each game and call me a fenian this and that.. i am a PROUD FENIAN no c@#t will ever change that, so sing away", he added.
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