March 1821. The brave insurgent Greeks hoist the sacred banner of the revolution against the Ottoman Empire in the monastery of Agia Lavra in Kalavryta.March 1821. The brave insurgent Greeks hoist the sacred banner of the revolution against the Ottoman Empire in the monastery of Agia Lavra in Kalavryta.March 1821. The brave insurgent Greeks hoist the sacred banner of the revolution against the Ottoman Empire in the monastery of Agia Lavra in Kalavryta.