Battle of Cadfan The Battle of Cadfan was fought in 1257 between English and Welsh forces . The Battle consisted of two military engagements ; one at Coed Llathen and the other at Cymerau . The word Cadfan is a combination of the Welsh words ' Cad ' ( meaning battle ) and ' fan ' ( meaning place / area ) , with ' Cadfan ' directly translating to ' place of battle ' . Background . In the years before the battle Llywelyn ap Gruffydd of Gwynedd had been rapidly gaining power . Llywelyn had received much support from the lords of Deheubarth Maredudd ap Rhys and Maredudd ap Owain during the campaign , and as a reward for their loyalty , he gave them land that he had stripped from their nephew , Rhys Fychan ( who was a supporter of the English king ) . Prince Edward ( recently appointed Earl of Chester ) had noticed Llywelyn ' s growing power and raised an army in an attempt to counter the potential threat of Llywelyn . Edward had support from several English nobles , however he had little aid from his father , Henry III of England . The forces Edward ( led by the English nobles Stephen Bauzan , Lord of Breigan and Llansannor and Nicholas FitzMartin , Lord of Cemais ) invaded Wales with a large army of English , Gascon and south Welsh troops in an attempt to restore Rhys and to halt Llywelyn ' s growing power . The English preparations and advance . The English army was transported by sea and landed near Carmarthen . On Tuesday 29 May 1257 , the English army was assembled . The army was made up mainly of soldiers from England , but their ranks were bolstered by local English and Gascon colonists as well as some Welsh soldiers and mercenaries . The following Thursday , the English army marched towards Llandeilo through the Towy valley suppressing Welsh opposition and pillaging and destroying Welsh settlements . The English plan was to force the nearby fortress , Dinefwr Castle to surrender through intimidation . The battle . The first day . On Friday night , the English army encamped in the vicinity of Llandeilo Fawr . Maredudd ap Rhys and Maredudd ap Owain had armies hidden in the woods which had followed the English army . The Welsh army harassed the encamped English constantly with a combination of arrows , spears and intimidating sounds . The English suffered some casualties , and since morale was low , Stephen Bauzan quickly sent Rhys Fychan ( who had guided the army ) to negotiate with Dinefwr castle ' s garrison . However , Rhys is said to have either been seized by the garrison or to have betrayed the English . Either way , the English army had now lost its guide . The second day . The Battle of Coed Llathen . Lacking a guide , the English army decided to march back to Carmarthen . The Welsh armies in the woods hit the English with devastating guerrilla attacks ( using mostly bows or javelins ) from the first hour of Saturday right up until midday . There was an engagement between the two forces at midday which saw the Welsh troops outflank the English and successfully capture the English supply train at Coed Llathen . Although there seem to have been few casualties , the engagement at Coed Llathen swung the balance in favour of the Welsh since the English had lost most of their provisions . The Battle of Cymerau . Following their defeat at Coed Llathen , the English army retreated westward towards Cymerau . The land at Cymerau was ideal for the Welsh since it contained ravines and heavily wooded areas which would allow the Welsh to ambush the English with ease . The land was also wet and marshy meaning that the English knights would have trouble riding over it . The Welsh ambushed the English with their full army and a bloody battle ensued . Many English were said to have been torn from their mounts and trampled to death by the Welsh army . Stephen Bauzan was killed along with around 1 , 000 – 3 , 000 of his men ( the amount killed varies with the source ) . The remaining Englishmen fled the battle . Llywelyn ap Gruffydd , King of Gwynedd is said to have been present at the battle , collecting spoils from the fallen English army . Aftermath , later conflicts , and the Treaty of Montgomery . The victory at Cadfan allowed the Welsh forces to take the castles of Laugharne , Llansteffan and Narbeth . Rhys Fychan hastily made his peace with Llywelyn , and Llywelyn returned Rhys ' s lands to him . There was a problem , however : Maredudd ap Rhys and Maredudd ap Owain had now been stripped of their new land . The two therefore switched sides and paid homage to Henry later that year . King Henry ( who had originally viewed Llywelyn ' s rising as only a small rebellion ) was shocked . Henry quickly realized the seriousness of the situation and personally organized another attack on Wales during the same year . This attack also proved unsuccessful when supply ships from Ireland failed to reach Henry and Edward ' s invading army . Lacking food and supplies , the English army was forced to retreat , being constantly harassed by victorious Welsh guerrilla fighters on the way back . Edward launched yet another invasion of Wales in 1262 following Llywelyn ' s raids in the Welsh Marches . Edward , however , was forced to pull his armies out of Wales due to internal conflicts in England . Llywelyn retaliated by campaigning against the English Marcher Lords in a devastating campaign which led King Henry ( who had been considerably weakened by the Second Barons ' War ) to open negotiations with Llywelyn at the Treaty of Montgomery which won Llywelyn much land at the expense of the defeated Marcher Lords .