Complex sentence: On 19 December 1961, the Indian Army began military operations with Operation Vijay resulting in the invasion and annexation of Goa, Daman, and Diu and forcefully incorporating the regions into the newly formed Indian union.
Split into simpler sentences: On 19 December 1961, the Indian Army invaded with Operation Vijay. This resulted in the annexation of Goa, Daman, and Diu into the Indian union.