Originally built in 1283 and a sister castle to the one across the bay at Criccieth, Harlech Castle has the honour of being at the heart of the longest known seige in British history, which lasted seven years between 1461 and 1468 while under the command of Constable Dafydd ap Ieuan. The War of the Roses was raging and the Lancastrian forces inside the castle held out long after other garrisons had caved in. Eventually, famine forced their surrender to Lord Herbert of the Yorkist faction, but only after the negotiation of favourable terms.
This was not the first seige to be endured by Harlech Castle, but the length makes it memorable and the event was recounted in a famous Welsh song; "Men of Harlech" or "The March of the Men of Harlech" (in Welsh: Rhyfelgyrch Gwŷr Harlech), which has become the regimental march of several regiments associated with the country, including two from Canada and two from Australia. It has also featured in several films; most notably the 1964 account of an event in the South African Boer War "Zulu".
There are several versions of the song. To hear it in English, follow this link or if you fancy hearing the Welsh, as sung by the Treorchy male Choir, try here.