f the Cotentin, which comprehended near a third of the duchy of
Normandy. Robert afterwards, upon some suspicion, threw him into prison;
but finding himself exposed to invasion from the king of England, ind
dreading the conjunction of the two brothers against him, he now gave
Henry his liberty, and even made use of his assistance in suppressing
the insurrections of his rebellious subjects. Conan, a rich burgess of
Rouen, had entered into a conspiracy to deliver that city to William;
but Henry, on the detection of his guilt, carried the traitor up to a
high tower and with his own hands flung him from the battlements.

The king appeared in Normandy at the head of an army and affairs seemed
to have come to extremity between the brothers, when the nobility on
both sides, strongly connected by interest and alliances, interposed,
and meditated an accommodation. The chief advantage of this treaty
accrued to William, who obtained possession of the territory of Eu, the
towns of Aumule, Fescamp, and other places; but in return he promised,
that he would assist his brother in subduing Maine, which had rebelled;
and that the Norman barons, attainted in Robert's cause, should be
restored to their estates in England. The two brothers also stipulated,
that, on the demise of either without issue, the survivor should inherit
all his dominions; and twelve of the most powerful barons on each
side swore that they would employ their power to insure the effectual
execution of the whole treaty,[*] a strong proof of the great
independence and authority of the nobles in those ages.

[* Chron. Sax. p. 197. W. Malms, p. 121. Hoveden,
p. 462. M Paris, p. 11. Annul. Waverl. p. 137. W. Heming. p.
463. Sum Dunelm. p. 216. Brompton, p. 986.]

Prince Henry, disgusted that so little care had been taken of his
interests in this accommodation, retired to St. Michael's Mount, a
strong fortress on the coast of Normandy, and infested the neighborhood
with his incursions. Robert and William, with their joint forces,
besieged him in this place, and had nearly reduced him by the scarcity
of water, when the elder, hearing of his distress, granted him
permission to supply himself, and also sent him some pipes of wine for
his own table. Being reproved by William for this ill-timed generosity,
he replied, "What, shall I suffer my brother to die of thirst? Where
shall we find another when he is gone?" The king also, during this
siege, performed an a