During the Cretan Revolution of 1866-1869, the Ottoman Empire was forced to send several pashas in Crete, but the effort proved fruitless. The latest Pasha sent to the island was Avni Pasha, who faced the continuing resistance of the Cretans and decided to change his operational tactics.
Thus, the measures he took were:
- He provided political protection to those who declared allegiance to the muftis.
- The Turkish fleet ruled the northern coast of Crete, so as to stop supplies coming from Greece.
- Put a price on the Cretan rebels, with 500 ottoman pounds each.
- He settled Kurds and Circassians to the island, in order to strengthen the Muslim population.
- He designed an entire system of large and small towers (called koules) in prominent locations throughout Crete, in order to fully control the island.
Specifically, Crete was divided into five provinces, the governors of which undertook the construction of koules. The koules were built on high hills, crossroads, ports, passages and their guards spied the rebels and the transporting Christians. They intercommunicated (with fanfare or fire) in case of an emergency and delivered the alert message serially to the main camp (called Kiesle). The effectiveness of Koules was devastating for the Cretans, as they could no longer easily intercommunicate.
The Cretans reacted actively during the erection of the towers, harassing the builders, destroying the buildings in the evenings or destroying lime furnaces, from where the Turks supplied lime for building. Nevertheless, Avni Pasha managed to complete his project by using experienced Bulgarian and Armenian craftsmen, who until August 1868 had built more than 60 koules and 2 months later this number increased to 150.
As mentioned, the Turks called these towers koules, after the Turkish kule. The only difference between them and the rest towers of the island is that koules were built by the state, rather than by private feudal lords and onwers (mainly Venetian).
The Cretans, while trying to free themselves, destroyed several Koules, many of which do not currently exist. However, dozens of areas on Crete have relevant place names (koule or pirgos (tower)), that implies the former existence of towers. Due to the large number of the Koules, here we will not deal with all of them, but a few that still exist.
The Turkish forts of Fodele 
Plakias Koules 
One of the many Turkish towers (Koules) built by the Turks in Crete is that of Plakias at South Rethymno. It was built on a hill of conglomerate grounds, with steep cliffs at its east and south sides, inside a fortified enclosure.
The most important passage of Rethymnon prefecture was that of Agios Vasilios (south), through where Turks and Greeks traveled from Mesara plain to Sfakia area. Thus, several towers (kouledes) were built. Such one Koules was built near the entrance of the gorge Kourtaliotis, near the village Koxare. The tower was partially destroyed by the Cretan rebels in 1896.
At the eastern edge of the valley of Amari, two towers were built, the Koules of Vathiakos and Lochria. The Koules of Vathiakos, built on the hill south of the village, served a dual purpose. First, it controlled the passages to Messara.
One of the many defensive towers (koule) built by the Turks at the strategic places that controlled the passages between the different regions of Crete and was the Koule of Meronas, next to the current church dedicated to Prophet Elijah. The point has panoramic views to the valleys of Amari and Potami. The Koule survives in bad condition.
At the small valley of Kamares - Grigoria - Magarikari were the Koules of Grammeni and the Koules of Kremastos. The first was built between Grigoria and Magarikari, next to the current road. It is in good condition, with almost all of its roof surviving.
At an altitude of 705m, between the village Ano Moulia and the ruined village of Raftis, at a point that controls the valley of Messara, in 1866, Avni Pasha built a large Koules for controlling the passage to Messara and to protect Raftis, which was a Muslim village.
Above Episkopi, province Ierapetra, we meet one Ottoman Tower (Koules), one of the many built in 1868 by the ottoman Avni Pasha. The defensive tower was built there to control the passage of the isthmus of Ierapetra.
In the Province of Selino (the wider area of Paleochora), in Sougia Koyles were built in the positions Boukelasi, Koustogerako, Kefala in Rodovani (ancient Elyros), Stavros near Kantanos, Moustakos, Spaniako and Vigles. The Koules of Spaniako controlled the valleys, the passages and the towering peaks around it, while on the south lies the Libyan Sea.
