Dumbarton Castle (Scottish Gaelic: Dùn Breatainn, pronounced [t̪unˈpɾʲɛʰt̪ɪɲ]; Welsh: Alt Clut) has the longest recorded history of any stronghold in Scotland.

However the first written record about a settlement there was in a letter that Saint Patrick wrote to King Ceretic of Alt Clut in the late 5th century.

David Nash Ford has proposed that Dumbarton was the Cair Brithon ('Fort of the Britons') listed by Nennius among the 28 cities of Sub-Roman Britain.

The medieval Scalacronica of Sir Thomas Grey recorded the legend that says that "Arthur left Hoël of Brittany his nephew sick at Alcluit in Scotland.

[7] Amongst lists of three things, in the triads of the Red Book of Hergest, the third "Unrestrained Ravaging" was Aeddan Fradog (the Wily, perhaps Áedán mac Gabráin), coming to the court of Rhydderch the Generous at Alclud, who left neither food nor drink nor beast alive.

He later safely conveyed the royal couple to greater safety in France, attended by his daughter Evota Fleming, as Maid of Honour.

The king and queen remained in France for eight years, but Malcolm Fleming returned to Dumbarton and continued to hold it safely against an English siege.

[12] Following his own death a year later he was succeeded as Sheriff of Dunbartonshire and Governor of Dumbarton Castle by his nephew, Malcolm Fleming of Biggar.

He marched on the town of Dumbarton and burned it, but was unable to take the castle, whose defender Sir John Colquhoun successfully held out against James' men.

The former supporters of James III under the leadership of John Stewart, 1st Earl of Lennox met up at Dumbarton Castle in October 1489.

[18] In September Regent Albany held court at Dumbarton, and received Thomas Benolt, the English Clarenceux King of Arms.

This expedition was later published by Nicolas de Nicolay Seigneur d'Arfeville, cosmographer to the King of France in 1583, with the first modern map of Scotland's coastline.

[24] Matthew, Earl of Lennox had been an ally of the French party in Scotland led by Mary of Guise but committed himself to the pro-English faction.

In 1544 munitions and ten thousand French crowns of the sun arrived with Jacques de la Brosse at Dumbarton's harbour and were secured by Lennox and the Earl of Glencairn.

Despite this, more French troops landed at Dumbarton under the leadership of Lorges Montgomery, the soldier who later killed Henry II of France at a joust in 1559.

[26] Regent Arran besieged the castle with a superior force, having borrowed the artillery of the Earl of Argyle and ordering Robert Hamilton of Briggis to bring guns from Dunbar.

The chronicle historian John Lesley wrote that the Captain and the Bishop surrendered the castle to Arran and were rewarded, after negotiation by the Earl of Huntly.

Alexander Cunningham, 5th Earl of Glencairn wrote to Mary of Guise from Dumbarton that he had received a French cargo, and it would be as safe as if it were in Stirling Castle.

According to a rumour heard by Gilbert Kennedy, 3rd Earl of Cassilis, five hundred Gascon soldiers arrived at Dumbarton destined to serve on the borders against the English for Mary of Guise.

When William Kirkcaldy of Grange governor of Edinburgh Castle changed sides to support Mary, this became a problem for Regent Moray.

[37][38] In October 1570 during the Marian civil war Fleming fortified the castle for Mary against the supporters of James VI of Scotland with stones obtained by demolishing churches and houses in Dumbarton and Cardross.

[39] The castle was captured by the forces of Regent Lennox led by Thomas Crawford of Jordanhill and John Cunningham of Drumquhassle in the early hours of 2 April 1571, who used ladders to scale the rock and surprise the garrison.

[40] Lord Fleming escaped by sea but died a year later when accidentally wounded by friendly fire as he supervised the supply of additional munitions at Edinburgh Castle.

The Duke of Lennox was displaced by the Gowrie Regime and went to the castle in secret pretending to be travelling from Edinburgh to nearby Dalkeith Palace.

Robert Bowes, the English resident agent, expected the Duke of Lennox would sail to France from Dumbarton "having well victualled his shippe there."

[43] By 1620, Sir John Stewart, an illegitimate son of the 2nd Duke of Lennox, had been made constable and keeper of Dumbarton Castle.

[44] In November 1645 the Committee of Estates approved the recruitment of thirty extra soldiers by the keeper John Semple to guard the increased number of prisoners.

However, due to threats posed by Jacobites and the French in the eighteenth century, new structures and defences were built and the castle was garrisoned until World War II.

[49] The document compiled in 1580 was "the inventar of the munitioun and uther insicht geir underwrittin left in the castell of Dumbertane be Johnne Conninghame of Drumquhassill and deliverit be the said Johnne to William Stewart of Cabirston in name and behalf of ane noble and potent lord Esme erll of Lennox lord Darnley and Obeigny on the 27 August 1580".

[88] In 1803 Dorothy and William Wordsworth visited the castle and were told that a ruin on the top of the highest eminence had been a windmill and were shown a trout, boxed up in a well close by to the guard room, that had been there for thirty years.