The month of October, illuminated by the feast of Our Lady of the Rosary on October 7, was named the month of the Rosary and dedicated to "the Holy Queen of the Rosary" by Pope Leo XIII in 1883. The feast of Our Lady of the Rosary, which prompted this dedication, was instituted by Pope St. Pius V (1504-1572) to commemorate the victory of Lepanto on October 7, 1571. This victory was attributed to the prayer of the Rosary and inscribed in the liturgy by Pius V and his successors.
The Battle of Lepanto took place on October 7, 1571, in the eastern Mediterranean. It involved a coalition of Christian naval forces opposing a growing Turkish fleet that was posing a threat to Western Europe.
For years, Pope Pius V had sounded alarms about the dangerous Muslim fleet expansion, and in May 1571, he succeeded in establishing what he called the "Holy League", an alliance of Spain, Venice and Malta, which he consecrated in St. Peter's Basilica.
An imposing fleet was gathered and entrusted to Don Juan of Austria, brother of Philip II of Spain. In order to implore heavenly protection for the fleet, St. Pius V ordered a solemn jubilee, a fast and the public prayer of the rosary.
The decisive battle took place on October 7, 1571, in the Gulf of Lepanto, at the exit of the Straits of Corinth. It involved 213 Spanish and Venetian galleys and some 300 Turkish vessels. About 100,000 men fought on each side. The Christian fleet won a complete victory, thanks to its heavy artillery.
The thrill caused in the West by this unexpected victory was immediately amplified by its religious repercussions, and this miraculous victory was attributed to the prayer of the Rosary.
Isabelle Rolland (Source: Marian Encyclopedia, mariedenazareth.com)