Vijaya Dashami also known as Dasara, Dashahara, Navaratri, Durgotdsav... is one of the very important & fascinating festivals of India, which is celebrated in the lunar month of Ashwin (usually in September or October) from the Shukla Paksha Pratipada (the next of the New moon day of Bhadrapada) to the Dashami or the tenth day of Ashwin.
In India harvest season begins at this time and as mother earth is the source of all food the Mother Goddess is invoked to start afresh the new harvest season and to reactivate the vigor and fertility of the soil by doing religious performances and rituals which invoke cosmic forces for the rejuvenation of the soil.
On the day of Dasha-Hara, statues of the Goddess Durga are submerged in the river waters. These statues are made with the clay & the pooja is performed with turmeric and other pooja items, which are powerful disinfectants and are mixed in the river waters. This makes water useful for the farmers & yields better crops.
Chatrapati Shivaji Maharaj, the founder of the Hindawi (Hindu) Swarajya - Maratha Empire used to always worship Lord Shiva & Goddess Durga in the form of goddess Bhawani before any military expedition. Goddess Bhavani had blessed Shivaji Maharaj with her own sword called "Bhavani Talwar" on this blessed day.
Buses, trucks and huge machines in factories are all decorated and as Dasha-Hara is also treated as Vishwakarma Divas - the National Labor Day of India.
Veda Vyasa is considered as the foremost Guru and Vijayadasami is also celebrated as Vyasa puja.
Dasha-Hara is the festival of Victory of Good over Bad, God over Devil