Several dates have been assigned for his birth and death, but he
probably flourished between 500 and 580, and his book, _De Excidio
Britanniae_ seems to have been written about 560. This work is a sketch
of British history under the Romans and in the period after their
withdrawal from the country, and includes the period of the wars of the
Britons with the Picts, Scots and Saxons. Mr Skene suggests very
reasonably that the well-known letter of the Britons to Aetius, asking
for Roman aid, is misplaced, and that if put in its own place some of
the anachronisms of Gildas will disappear. This work, which contains
some spirited attacks on the leaders of the Britons for their sins, is
strangely full of contradictions. It seems to be the work of some person
well versed in the facts of that part of British history, to which he
had an easy access, but who supplemented them with traditional details
and with dates which were mere guess-work. Mr Skene thinks that the work
of Nennius was originally written in Welsh in the north and was
afterwards translated into Latin. To this nucleus was added the
genealogies of the Saxon kings down to 738. Afterwards some person,
called Marc in the Vatican manuscript, appended probably about 823 the
life of St Germanus and the legends of St Patrick, which were
subsequently incorporated with the history. Some South Welshman added to
the oldest manuscript of the history in these countries, about 977, a
chronicle of events from 444 to 954, in which there are genealogies
beginning with Owain, son of Hywel Dda, king of South Wales. This
chronicle, which is not found in other manuscripts, has been made the
basis of two later chronicles brought down to 1286 and 1288
respectively. It is consequently not the work of one author. A learned
Irishman named Gilla Coemgin, who died in 1072, translated it into Irish
and added many things concerning the Irish and the Picts. The _Historia
Britonum_ is more valuable for the legendary matter which it contains
than for what may be accepted as history, for it gives us the British
legends of the colonization of Great Britain and Ireland, the exploits
of King Arthur and the prophecies of Merlin, which are not found
elsewhere before the 12th century. The date of the book is of the
greatest importance to the history of medieval romance, and there can be
no doubt that it is earlier than the Norman Conquest and that the
legends themselves are of British origin.

2. _The Epic