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The Legend Of The Fianna: Some Of The Mightiest Warriors From Irish Mythology

The Legend Of The Fianna: Some Of The Mightiest Warriors From Irish Mythology

Like many kids growing up in Ireland, stories of the Fianna and one of their legendary leaders, Fionn MacCumhaill, played a big part in my bedtime stories.

The Fianna were a fierce band of warriors that roamed around Ireland and tales of their adventures make up most of what is known as the ‘Fenian Cycle’ in Irish mythology.

In the guide below, you’ll discover who the Fianna were, what they stood for, who led them over the years and what stories and legends were associated with them.

Who were the Fianna in Irish Mythology?

So, the Fianna that you’ve come to know from Irish myth are a band of warriors that roamed Ireland. Up until five or six years ago, I believed that the story of the Fianna was completely based on myth.

Then, during a random conversation with a friend about Irish folklore, I was shown a 17th century book by a man named Geoffrey Keating, titled ‘Foras Feasa ar Éirinn’.

The book, which was published in and around 1634, is a history of the kingdom of Ireland and it offers insight into the story of our island, from the creation of earth right the way through to the coming of the Normans.

Fact or Fiction?

Now, it’s also worth mentioning that in early medieval Irish law, there are references to a group of men and women known as the ‘Fiann’. These were young people who were said to be ‘landless’ / yet to inherit land.

Although Keating’s book is often criticised as not being a reliable history of Ireland, it’s clear that there was a group similar to the Fianna in Ireland as it was referenced in early Irish law records.

In his book, Keating explains that during the winter, the Fianna were housed and fed by local nobility in exchange for them keeping law and order amongst their land.

During the summer, Keating explained that the Fianna were left to live off the land, hunting for food and things that they could trade.

Notable Members of the Fianna

There were many members of the Fianna over the years. From the legendary Fionn Mac Cumhaill who was the last leader of the group to Fionn’s son, Oisin, a talented poet who met his demise in the story of Tir na nOg.

Below, you’ll discover the most notable member of the Fianna, each of which lived by three mottoes; Purity of our hearts. Strength of our limbs. Action to match our speech:

Fionn mac Cumhaill

Fionn mac Cumhaill was the last man to lead the mighty band of warriors known as the Fianna. Fionn is arguably one of the most prominent figures in Irish folklore, alongside the mighty Cú Chulainn.

Fionn was at the centre of many stories from the Fenian Cycle of Irish Mythology. Some of the best-know tales are the Salmon of Knowledge, the Giant’s Causeway Legend and the Pursuit of Diarmuid and Grainne.

Fionn Mac Cumhaill was as intelligent as he was strong and was a skilful and celebrated fighter. In the Salmon of Knowledge, he becomes the most knowledgable man in Ireland and in The Legend of the Causeway he uses his wisdom to conquer a much stronger opponent.


Cumhall mac Trénmhoir was Fionn Mac Cumhaill’s father and he led the Fianna prior to Goll Mac Morna taking over. The most notable appearance of Cumaill is in Fotha Catha Chnucha, which translates to the ‘Cause of the Battle of Cnucha’.

It’s believed to have been written at some point during the 12th century. It’s here that Cumhaill is said to be the son of a very petty king in Ireland.

In the story, Cumaill became a suitor for the daughter of a druid named Tadg mac Cuadat. However, the druid refused his daughters hand in marriage. Cumhaill was infuriated and proceeded to pick the girl up and carry her away.

Goll mac Morna

I always disliked this next fella. Goll mac Morna was another previous leader of the Fianna. Now, in order to secure his place at the top of the totem pole, he killed Fionn’s father, Cumhall.

From the stories that I’ve been told and from the many that I’ve read about the Fianna, I’ve never come across any sense that Fionn held it against Goll, which seems strange.

Goll was the last leader of the Fianna before Fionn. It’s said that when Fionn grew into a man Goll realised that he was a more worthy leader, and that’s when Fionn Mac Cumhaill took the reins.

Caílte mac Rónáin

Caílte mac Rónáin was one of Fionn’s nephews. He was known to be able to move at lightning speed and was also revered for his ability to speak with animals. Caílte was also one of two that survived the final battle that led to the demise of the Fianna (more on this below).

Caílte mac Rónáin was one of the Fianna’s great storytellers and poets, and many of the poems to come from the Fenian Cycle of Irish mythology were written by Caílte.

Conán mac Morna

We used to have a teacher in school that people referred to as ‘Conán’, as we were told as kids that ‘Conán mac Morna’ was also known as Conan ‘the Bald’. Stupid, I know!

Conán mac Morna was another member of the Fianna but, unlike the others, he was said to be a bit of a clown.

Conán is often portrayed as a bit of a comedy act in the Fenian Cycle and as a troublemaker. However, with that being said, he is loyal to his leader and brave until the end.

Diarmuid Ua Duibhne

If you read our guide to the pursuit of Diarmuid and Grainne, you’ll be more than familiar with Diarmuid Ua Duibhne. Diarmuid is best known for his betrayal of Fionn Mac Cumhaill.

Fionn was set to marry Grainne, the daughter of the high king of Ireland, Cormac Mac Art. Then Diarmuid ran away with her. If you’d like to read more about Diarmuid, you can do so here.


Oisín was Fionn’s son and he is arguably best known for his lead part in the story of Tir na nOg. It’s said that Oisín got his name from his mother, Sadhbh. One day, Sadhbh was transformed into a deer by a wicked Druid.

She was caught by Fionn while he was out hunting one morning. He didn’t kill her and she soon turned back into her previous form. Fionn and Sadbh became a couple and soon after Sadbh became pregnant.

Then the evil Druid turned her back into a deer and she ran away. It’s said that many years later Fionn found Oisín on Benbulben mountain.


Oscar was the son of Oisin and grandson of Fionn. Oscar was a central figure in many of the legends that came from the latter end of the Fenian Cycle of Irish mythology.

In one story, Oscar is said to have battled the King of the World in a fight for the ford of Shannon. Oscar is said to have overpowered the king and that he cut his head clean off.

Oscar was one of the many members of the Fianna to be killed in the Battle of Gabhra. Upon his death, Fionn Mac Cumhaill shed the first tear of his life.

The Fianna Entrance Test

Joining the Fianna wasn’t a decision that one took lightly. Those who were accepted into the group were members for life – there was no change of hearts allowed.

Only the strongest and cleverest of men were accepted into the Fianna, so a rigorous test was put in place to separate those worthy of admittance from the many who sought to join.

Once a man was deemed worthy to join, there was a ceremony that had both immense symbolic and legal significance. Those that tried to leave would be seen as a traitor to their fellow members.

1. Intelligence

The first test that those looking to join the Fianna were given was one that put their intellect to the test. Men were required to be knowledgeable of the twelve books of poetry, which detailed the legends, history and genealogy of Ireland.

Members of the Fianna were gifted poets, storytellers and musicians. It’s believed that one of the reasons that they were greeted into homes across Ireland was due to the entertainment that they could provide.

Those that offered the Fianna a seat at their table would be treated to an evening of incredible stories, mesmerising poetry and music that’d soothe the soul.

2. Defence 

Once the first test had been passed, the man would move onto the physical challenges, which were brutal and tricky. The first was to prove that he could defend himself adequately.

He was required to stand tall in a deep hole and protect himself within just a shield and a staff. He then had to defend himself from being struck by spears thrown by nine competent warriors. 

3. Speed

The next test assessed the candidate’s speed and agility. He would be given a generous headstart into a forest and he would be required to evade capture from a band of fierce pursuers.

The candidate must escape unharmed. Now, that’s not all – he must escape the forest without breaking one single branch. No mean feat when you’re running at full speed.

4. Movement

Next up was the movement test. If the candidate made it this far, he would be required to successfully leap over trees that stood at the same height as he.

He was also required to show that he could stoop as low as his knee and make his way under the branch of a tree that stood just above shin height.

5. The Removal of a Thorn

The next test to enter the Fianna combined a need for speed with a need to preserve oneself during battle. Candidates were required to sprint as fast as they could with a thorn stuck in their foot.

This test was made all the more difficult by the requirement that the candidate must remove the thorn without slowing down at any point.

6. Bravery

The final physical test to become a member of the Fianna required a candidate to face a large number of men without letting his bravery falter for even a second.

This test was to ensure that the man would never back down, even when the Fianna were greatly outnumbered in battle. Once he passed this test, he moved onto the final hurdle.

7. Chivalry

The last test in becoming a member of the Fianna was all about character. The Fianna were a much-admired group, and each member must act accordingly.

Candidates were required to accept a number of terms that, once agreed upon, would see them accepted into the brotherhood of Irish warriors.

Members of the Fianna must not marry out of greed. Land and riches should not come into the equation. They must marry only for love. They were also required to be courteous with women and to never hoard something that another needed.

Cath Gabhra/The Battle of Gabhair: The Death of the Fianna

One of the questions that tends to pop up quite a bit online is ‘How did the Fianna die?’ Well, their demise all began with the Battle of Gabhair.

Now, as I’ve mentioned a couple of times above, I’m telling you the story that I was told – there are many different versions of the story of Cath Gabhra both online and offline.

The story all begins with a man named Cairbre Lifechair. Lifechair was the son of Cormac mac Airt, the High King of Ireland. His daughter was engaged to the prince of the Deisi (a class of people during ancient Ireland).

The prince, Maolsheachlainn, ended up being killed by two of his father-in-law-to-be’s sons, which ended the marriage before it ever began.

Enter the Fianna

It’s within this story that the Fianna is first shown in a negative light. The band of warriors were due to revive a large tribute from Cairbre after his daughter married the prince.

After the prince’s death, the marriage was no more. So, surely, there would be no reason for the tribute to be paid?! However, Fionn mac Cumhaill and the Fianna didn’t see it that way.

They demanded that the tribute be paid regardless. Cairbre was furious. It was clear that the power that the Fianna had amassed had gone to their heads, and he wasn’t going to stand for it.

Cairbre summoned an army of men from across Ireland. A group of men that were loyal to Goll mac Morna, an enemy of Fionn Mac Cumhaill, also joined.

The Final Battle

The battle is said to have taken place in either what is now Garristown in Dublin or in nearby Meath, on the hills of Skryne and Tara. Right, back to the battle.

The fight began when Cairbre slew Ferdia, Fionn’s loyal servant. Oscar, Fionn’s grandson and one of the Fianna’s fiercest warriors, went up against Cairbre and, although he killed the king, he was fatally injured himself.

The battle continued and the Fianna were overpowered and outmanned by a stronger force. In some versions of the story, the battle ends when Fionn Mac Cumhaill is killed as he mourns for Oscar.

The only two members of the Fianna to survive were Oisín, Fionn’s son, and Caílte mac Rónáin. The pair are said to have lived for many years and that they recounted the story of the battle to St. Patrick.

Discover many more tales and legends in our guides to the most popular Irish myths and the creepiest stories from Irish folklore.

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