Umm... I thinks that that there was this big unification war with all the major countries taking part. The war was fought on Land, Sea, Air, and most importantly, Space. Any country controlling space could easily fire down at any target on earth.
English (or German) becomes the standard language of Europe. Europe then allies with America to take over the world with their spacefleets. The survivors that speak a foreign tounge are forced to speak "Terran standard", this is all done for the sake of effieciency, so an interstellar society can always communicate with each other. This takes place just after the discovery of subspace when all the countries were fighting over the jump node. Think about it, any country that controls the node can reel in massive amounts of pofit with taxes, fares, trade agreements, etc. So it makes sense that every major country is so desperate to control the node.