The area around Criccieth was settled during the Bronze Age, and a chambered tomb, Cae Dyni, survives on the coast to the east of the town; it consists of seven upright stones, and there are 13 cup marks, arranged in several groups.
Evidence from other sites on the Llŷn Peninsula suggests that the area was colonised by a wave of Celtic settlers, who explored the Irish Sea, probably around the 4th century BC.
Ptolemy calls the peninsula Ganganorum Promontorium (English: Peninsula of the Gangani); the Gangani were a tribe of Irish Celts, and it is thought there may have been strong and friendly links with Leinster.

Although it is thought that Criccieth Castle was built around 1230 by Llywelyn ab Iorwerth, who had controlled the area since 1202, the first record of the building was in 1239, when the administrative centre of Eifionydd was moved from Dolbenmaen.

In the later years of his life, Llywelyn turned his attention to his successor.
Welsh law stipulated that illegitimate sons had equal rights with legitimate sons; Llywelyn sought to ensure that Dafydd ap Llywelyn, his legitimate offspring, would inherit Gwynedd in place of his eldest, but illegitimate, son Gruffydd.
On Llywelyn's death in 1240, Dafydd sought to secure his position.
Dafydd was half English and feared that his pure Welsh half-brother would be able to gather support to overthrow him.
Gruffydd was held prisoner in Criccieth Castle, until he was handed over to Henry III of England in 1241, and moved to the Tower of London.

Dafydd ap Llywelyn died in 1246, without leaving an heir, and was succeeded by Llywelyn ap Gruffudd, his nephew.
Edward I had inherited the English throne in 1272, and in 1276 declared Llywelyn a rebel.
By 1277, Edward's armies had captured the Isle of Anglesey, and were encamped at Deganwy; the settlement, the Treaty of Aberconwy, forced Llywelyn to acknowledge Edward as his sovereign, and stripped him of much of his territory.
 Dafydd ap Gruffydd, Llywelyn's younger brother, attacked the English forces at Hawarden in 1282, setting off a widespread rebellion throughout Wales; Edward responded with a further invasion of Gwynedd, during which Llywelyn was killed on the battlefield at Cilmeri.

With the final defeat of Gwynedd, Edward set about consolidating his rule in Wales.
Criccieth Castle was extended and reshaped, becoming one of a ring of castles surrounding Edward's newly conquered territories.
A township developed to support the garrison and a charter was granted in 1284; the charter was intended to create a plantation of English burgesses who would provide food for the soldiers from the arable land behind the Dinas and the grazings on the slopes beyond.
Weekly markets were held on Thursdays and there were annual fairs on 25 April and 18 October, the evangelical feasts of Saint Mark and Saint Luke.

The new administration soon proved unpopular among the native Welsh, and in 1294, Madog ap Llywelyn led a national revolt against English rule.
Criccieth was besieged for several months over the winter; 41 residents sought refuge within its walls, joining the garrison of 29 men under William de Leybourne, until supplies were brought in from Ireland the following April.
The following year, the castle was again used as a prison, housing captives taken in Edward's wars against Scotland.

Three Welshmen who had settled in the borough, which was supposedly reserved for the English, were evicted in 1337, but times were about to change.
Hywel ap Gruffydd was appointed constable of the castle in 1359, the first Welshman to hold the post.
The following year came mayor of the town, holding the office for twenty years; in a poem of praise, Iolo Goch described him as "a puissant knight, head of a garrison guarding the land".
By 1374 eight jurymen from the borough had Welsh names.

Richard II was deposed and imprisoned in 1399, and died in mysterious circumstances the following year.
 Opposition to the new king, Henry IV, was particularly strong in Wales and Cheshire, and in 1400 serious civil unrest broke out in Chester.
Henry had already declared Owa
The area around Criccieth was settled during the Bronze Age, and a chambered tomb, Cae Dyni, survives on the coast to the east of the town; it consists of seven upright stones, and there are 13 cup marks, arranged in several groups. Evidence from other sites on the Llŷn Peninsula suggests that the area was colonised by a wave of Celtic settlers, who explored the Irish Sea, probably around the 4th century BC. Ptolemy calls the peninsula Ganganorum Promontorium (English: Peninsula of the Gangani); the Gangani were a tribe of Irish Celts, and it is thought there may have been strong and friendly links with Leinster.
Although it is thought that Criccieth Castle was built around 1230 by Llywelyn ab Iorwerth, who had controlled the area since 1202, the first record of the building was in 1239, when the administrative centre of Eifionydd was moved from Dolbenmaen.
In the later years of his life, Llywelyn turned his attention to his successor. Welsh law stipulated that illegitimate sons had equal rights with legitimate sons; Llywelyn sought to ensure that Dafydd ap Llywelyn, his legitimate offspring, would inherit Gwynedd in place of his eldest, but illegitimate, son Gruffydd. On Llywelyn's death in 1240, Dafydd sought to secure his position. Dafydd was half English and feared that his pure Welsh half-brother would be able to gather support to overthrow him. Gruffydd was held prisoner in Criccieth Castle, until he was handed over to Henry III of England in 1241, and moved to the Tower of London.
Dafydd ap Llywelyn died in 1246, without leaving an heir, and was succeeded by Llywelyn ap Gruffudd, his nephew. Edward I had inherited the English throne in 1272, and in 1276 declared Llywelyn a rebel. By 1277, Edward's armies had captured the Isle of Anglesey, and were encamped at Deganwy; the settlement, the Treaty of Aberconwy, forced Llywelyn to acknowledge Edward as his sovereign, and stripped him of much of his territory.  Dafydd ap Gruffydd, Llywelyn's younger brother, attacked the English forces at Hawarden in 1282, setting off a widespread rebellion throughout Wales; Edward responded with a further invasion of Gwynedd, during which Llywelyn was killed on the battlefield at Cilmeri.
With the final defeat of Gwynedd, Edward set about consolidating his rule in Wales. Criccieth Castle was extended and reshaped, becoming one of a ring of castles surrounding Edward's newly conquered territories. A township developed to support the garrison and a charter was granted in 1284; the charter was intended to create a plantation of English burgesses who would provide food for the soldiers from the arable land behind the Dinas and the grazings on the slopes beyond. Weekly markets were held on Thursdays and there were annual fairs on 25 April and 18 October, the evangelical feasts of Saint Mark and Saint Luke.
The new administration soon proved unpopular among the native Welsh, and in 1294, Madog ap Llywelyn led a national revolt against English rule. Criccieth was besieged for several months over the winter; 41 residents sought refuge within its walls, joining the garrison of 29 men under William de Leybourne, until supplies were brought in from Ireland the following April. The following year, the castle was again used as a prison, housing captives taken in Edward's wars against Scotland.
Three Welshmen who had settled in the borough, which was supposedly reserved for the English, were evicted in 1337, but times were about to change. Hywel ap Gruffydd was appointed constable of the castle in 1359, the first Welshman to hold the post. The following year came mayor of the town, holding the office for twenty years; in a poem of praise, Iolo Goch described him as "a puissant knight, head of a garrison guarding the land". By 1374 eight jurymen from the borough had Welsh names.
Richard II was deposed and imprisoned in 1399, and died in mysterious circumstances the following year.  Opposition to the new king, Henry IV, was particularly strong in Wales and Cheshire, and in 1400 serious civil unrest broke out in Chester. Henry had already declared Owa
Criccieth