Most of the opening two stanzas have been lost for the past 2,000 years, but research in the museum has recovered vital elements of the first lines of the epic. Scholars have been able to reconstruct the first four lines as follows:
"He who saw all, who was the foundation of the land,
"Who knew (everything), was wise in all matters.
"Gilgamesh, who saw all, who was the foundation of the land,
"Who knew (everything), was wise in all matters."
The discovery, made by Theodore Kwasman, an American expert on Mesopotamian language and script, is a key step towards a complete understanding of the 15,000-word work.
First written out as a set of clay tablets by at least the 18th century BC, it was re-copied many times over the following two millennia.
Hundreds of fragments of various editions of this set of tablets have been identified and fitted together like a giant jigsaw. But almost 20 per cent of the epic is still missing and a further 25 per cent is so fragmentary that it is only partially legible. Nevertheless, archaeologists are confident that the entire jigsaw will be completed, and that the work - known originally as Surpassing All Other Kings and later as The One Who Saw All, will once again be available in its entirety.
Missing lines are being discovered in museum collections world-wide and in excavations in the Middle East at the rate of several dozen words a year.
The Epic of Gilgamesh tells the story of an early 3rd-millennium BC Sumerian (southern Mesopotamian) king who went in search of the secret of everlasting life - a secret held by the survivor of the great flood, the proto-Noah, who had become immortal.
The newly identified Gilgamesh "first-lines" fragment is from an edition of the epic copied between 600BC and 100BC. The fragment was initially found in 1878, probably in the ruins of ancient Babylon either by commercial treasure hunters or by the British Museum's agent in Baghdad, Hormuzd Rassam, who 25 years earlier had helped the museum to excavate in what is now northern Iraq.
At that stage nobody realised what it was, and it (with many other tablet fragments) was shipped to the British Museum, where it was stored as a resource for scholars.
The material will be included in a new translation of The Epic of Gilgamesh due to be published in February by Penguin Books.
Discoveries Made in the Museum's Back Room
IDENTIFICATION of the Gilgamesh fragment is only one of dozens of archaeological discoveries made every year - inside the British Museum.
Most people probably think of it as simply a vast collection of display cases filled with antiquities, but nothing could be further from the truth.
Only 1 per cent of the objects are on view. The rest - 7 million objects - are kept in store rooms and constitute the world's largest archaeological research collection.
Every year more than 10,000 scholars carry out vital research on this vast stored collection. They examine up to 250,000 items, while British Museum staff carry out research into thousands more.
Recent breakthroughs at the museum have included:
The discovery of the earliest sword blade made of "crucible" extra- hard steel. Dating from the 7th century, it was identified using a metallographic microscope in the museum's research laboratory;
Identification of early coin forgeries and an understanding as to how they were forged;
The discovery that the red enamel used for decorating treasures in Dark Age Britain was made from metallurgical waste products;
Finding that a large fragment of ancient Egyptian manuscript was in fact the missing part of a papyrus in a French museum;
And the discovery that Romano-Egyptian portraits were painted after death.