Tens of millions of voters in Pakistan will head to the polls this week to choose a new government. It's been a tumultuous few weeks for the country of nearly 200-million people. Earlier this month, an anti-corruption court found former Prime Minister Nawaz Sharif guilty of corruption. His party is one of several contesting this election. If it all goes according to plan, it would be just the second time there's been a peaceful transfer of power from one civilian government to another. Pakistan has swung between civilian and military rule since its independence from Britain 1947. But what's the role of Pakistan's military in politics? and how powerful is it?