[cross-posted at Austro-Athenian Empire]

Writing of the defeat of the Byzantine forces at Brindisi in 1156, John Julius Norwich observes:

It was the same old lesson – a lesson that should by now have been self-evident, but one that the princes of medieval Europe seemed to find almost impossible to learn: that in distant lands, wherever there existed an organized native opposition, a temporary occupying force could never achieve permanent conquest. Whirlwind campaigns were easy, especially when backed by bribes and generous subsidies to the local malcontents; when, however, it became necessary to consolidate and maintain the advantage gained, no amount of gold was of any avail. ... The outcome of the recent campaign – however promisingly it had begun – had not been unlucky. It had been inevitable.
(Byzantium: The Decline and Fall (NY: Knopf, 1995), pp. 115-116.)