The " Fifth Column" is not an ancient word and was coined in the last century during the Spanish Civil War. This war took place between the Republicans and the monarchists and ultimately brought General Franco to power in Spain. General Franco was backed by Hitler and the civil war was a proxy war between the English and Germany. During this war a Nationalist general named Emilia Mola told journalists when his troops were converging on Madrid that he was advancing with 4 columns and a "fifth column" was in Madrid city itself, which would start an uprising and help him. In other words he used this terminology to define a group of people who were his close sympathizers and would help him. This was how the word got incorporated in the English language.
A fifth column has it's genesis in military terminology, but is now used not in the restricted sense, but as a definition for a group of people who betray national interests. Though this phrase is of recent origin, fifth columns have existed since the dawn of history. They are very relevant to India and one of the reasons for the subjugation of Hindu armies was the presence of fifth columns which sided with the enemy. Thus in 326 BC, when Alexander the Great invaded India the Raja of Taxila sided with Alexander against Porus. It is another matter that Porus held his own against Alexander and was the strategic victor. Alexander went back and gifted vast lands and riches to Porus.
In the 12the century the name of Raja Jaichand is famous as he sided with Mohammed of Ghor against the ruling monarch at Delhi, Prithviraj Chauhan. As late as 1757 during the famous battle of Plessey in Bengal between Robert Clive and the Nawab Siraj ud dowlah, his close aide and mentor Mir Jafar sided with the English to betray the interests of Nawab Siraj and handed a victory to Robert Clive on a platter. Mir Jafar has earned the title "Gaddar e Hind".
Fifth columns have existed in other nations as well and during the days of the Raj, the Maharajahs acted as a fifth column against national interests and Indian independence. Thus the phrase " fifth column" is very much applicable to India and denotes a group of people who work against national interests to facilitate a enemy victory.
The recent carnage in Paris where Wahhabi Sunni Mujaheddin targeted the French state is another example of a fifth column operating in France. The French minister of Culture has referred to the French Muslim community which actively aided the terror attack as well contributed manpower for it as a ' fifth column' against the ideals of the French republic. One must bear in mind that France has a population of 66 million and 6 million Muslims that constitute about 8-10 % of the population. Keeping their demographic growth rate and fertility, this will be 15% by 2030 and has alarmed the French.
The Muslim religion is an international concept and migrants who settle in a country are known to act as fifth column against the state. It has happened in Belgium and France and can happen anywhere. India in particular is the soft underbelly of this movement. Weak kneed policies has opened the gates for fifth columns to operate in India. Many Muslims sympathize with the Islamic state and some have even volunteered to join them. In Kashmir despite billions of dollars being poured into the valley by the central government, fifth columns that support Pakistan and carry out ethnic cleansing of Kashmiri Pandits and also fight the Indian state is rampant.
India, also like France, has a large Muslim minority and this minority may act as a fifth column in time to come. France is a well off welfare state that has no poverty and yet the Muslims have operated as a fifth column there. India with widespread poverty and lack of means of livelihood, the chance of this minority operating as a fifth column is that much more. I wonder what is the solution except greater vigilance as the enemy may be within.I will concede that one cannot brand an entire community or sect as a " fifth column", but the statement of President Obama in his press conference is food for thought. He stated that the majority in the Muslim community have done precious little to counter extremist Islamic philosophy. In India we have what we call "vote bank politics". This does not distinguish between religions and many Hindu leaders are guilty of serving the interest of a fifth column .