From Reuters.com :
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Sinai fort may hold clues to ancient Egypt defenses
Thu May 7, 2009 12:53pm EDT

By Alastair Sharp

QANTARA, Egypt (Reuters) - A military garrison of mud-brick and
seashells unearthed in Egypt's Sinai desert may be key to finding a
web of pharaonic-era defenses at the northeast gateway to ancient
Egypt, archaeologists said on Thursday.

Archaeologists who discovered the 3,500-year-old garrison, where up to
50,000 soldiers could be posted in times of heightened tensions, say
they hope inscriptions at Luxor's Karnak temple may serve as a guide
to finding other outposts.

But knowing the location of the garrison at the ancient city of Tharu,

in a formerly fertile area of Egypt where a branch of the Nile river
once met the Mediterranean Sea, is key to understanding where to start
looking.

"As we understand from the inscription at Karnak temple, the city of
Tharu had two fortifications with the Nile in the middle," said
Mohamad Abdul Maqsoud, who heads archaeological exploration in Egypt's
Nile Delta and Sinai regions.

In their 3,000-year history, Egypt's Pharaohs often ventured across
Sinai to fight Hittites and other civilizations in the area now
covered by Israel, the occupied Palestinian territories, Lebanon,
Jordan, Syria and Iraq.

"This city was used to protect Egypt and as a gate to the Delta. It
was a post of control. If you wanted to cross the Nile, you asked for
permission before you crossed the bridge," Abdul Maqsoud said.

Most Egyptian fortifications at the time were made of stone, not
easily available in the Sinai. So Egyptians used seashells to
strengthen the mud brick used to build the garrison, with a 15 meter
thick and 12 meter high wall to discourage attack.

GARRISON USED TO EXPEL HYKSOS

Abdul Maqsoud said a full exploration and excavation of possible
pharaonic military installations in Sinai could take 15 years to
complete, but he expected to find more outposts. The garrison, called
Tell Heboua, is now some 15 km (9 miles) from the coast and the Nile
branch is no longer there.

The fortress was first used as a base from which to expel the
occupying Hyksos, who occupied Egypt for some 120 years between 1620
and 1534 BC and whose capital, Avaris, was located nearby in the
Delta, Abdul Maqsoud said.

Their expulsion is seen as the beginning of the New Kingdom.

"When the Egyptians liberated Egypt it was a very important military
action against the city here by the King Ahmose I," Abdul Maqsoud
said.

The fortress later played a significant role in military actions
against the Hittites during the reign of Ramses II during the 19th
pharaonic dynasty.

Abdul Maqsoud said some 30,000 civilians lived in the adjacent city,
which was also a major trading post, and the site contains human and
crocodile remains, remnants of temple columns and broken pottery.

"They sold very good wine from this area in the pharaonic time. This
is described even in the tomb of Tutankhamun," Abdul Maqsoud said.

Abdul Maqsoud said Frenchman Ferdinand de Lesseps discovered a large
inscribed stone in the area during construction of the Suez Canal in
the 1850s and diverted the canal's path to preserve the site.

(Reporting by Alastair Sharp; Editing by Jon Hemming)