New Delhi/Srinagar, April 13 : The Indian Army observed the 36th Siachen Day on Monday, remembering the gallant martyrs of Siachen. Siachen Day commemorates the courage and fortitude displayed by troops of the Indian Army in securing the highest and coldest battlefield in the world. On April 13, 1984, the Indian Army launched 'Operation Meghdoot' to secure Bilafond La and other passes on the Saltoro Ridgeline from Pakistani aggression. "Since then, it has been a saga of unparalleled valour in the face of a belligerent enemy, arduous terrain and challenging climatic conditions," said the Indian Army. The Siachen Warriors continue to guard the 'Frozen Frontier' with tenacity and resolve against all odds. "The 'Siachen Day' every year honours all the Siachen Warriors who served their motherland while successfully thwarting evil designs of the enemy over the years," said the force. The force celebrates a saga of unmatched bravery, heroism, courage and sacrifice on the world's highest and coldest battlefield. Siachen lies in the Karakoram Range in North-West India. Siachen Glacier is 76.4 km long and covers about 10,000 sq km of uninhabited terrain. It was in 1974 that Pakistan started permitting mountaineering expeditions in the Siachen Glacier. By the spring of 1983, it was clear that India needed to maintain a close watch on Siachen. On this day, Indian Army raised the first Indian flag on Siachen Glacier at Bilafond La and thereafter began 'Operation Meghdoot'. /IANS