For eras, rivers began their free flows to the seas as trickles of streams in the uplands of their mountainous divides. As these rills and streams fervidly tumbled down unimpeded, they made their approach down the highlands and into the broad sweeping rivers, and then they continued to flow unto the flat lands. At no period in human history have the world’s rivers flowed freely and then hit a wall other than in the twentieth century. During that 100-year epoch, mankind as a manipulator was involved in a battle with the environment to subjugate and overcome it. This need to overpower and control nature, via dams and mega-dams, is the penultimate act of an “entire revolution” that has left no river free from human obstruction. This chapter provides the historical background to that saga.