Papagiannis organized a rebellion against Ottoman rule after the Battle of Lepanto (1571), where the Ottoman fleet was defeated by the Holy League.[2] He initiated correspondence with various Western European rulers, where he propagated that his compatriots were eager to cast off Ottoman rule. He also claimed that a victory could be easily achieved with the creation of an anti-Ottoman alliance with the local Greek subjects.[6] In 1572, after securing the support of various local Orthodox metropolitan bishops, especially Joachim of Ohrid, he moved to Venice. There he negotiated with Doge Sebastiano Venier for the possibility of Venetian involvement in the revolt.[7] In February–April 1572, a Venetian fleet of twelve galleys was ready to attack the coastal region of Delvine. However, Venier recalled the attack order, in fear that his manpower was not enough for a successful assault. The Venetian activity was limited to a minor raid against the coastal village of Mazaraki on the Ionian coast.[8] Nevertheless, Venice ultimately decided to make peace with the Ottomans and Papagiannis's proposals were dismissed.[7]
The following year, Papagiannis, together with another local noble from Argyrocastro, Panos Kestolikos, moved to Naples and asked the Spaniards to support their revolutionary plan. They also discussed the possibility of an anti-Ottoman armed struggle with the head of the Holy League, John of Austria, "as Greek representatives of enslaved Greece and Albania".[9][10][11] John was eager to provide the necessary support for an immediate revolt,[4] but the Spanish dismissed the plans. They provided only a limited amount of money to Papagiannis in exchange for remaining in their service as an agent.[11]
After the dissolution of the Holy League, both Papagiannis and Kestolikos approached Philip II of Spain (r. 1554–1558).[3] In 1574, Papagiannis was in Ottoman-controlled Epirus to prepare another planned revolt.[12] The following year, he was located in Himara, on the Ionian coast, together with Basque spy Antonio de Echavarri, in order to determine if the situation was ripe for that purpose.[13] Later, in 1577, he established contacts with Spanish spy Martin de Acuna in Constantinople.[14]