This two-part drama documentary tells the epic story of the Allies’ finest hour - and the invention of modern warfare. The first episode, The Spring Offensive, begins in early 1918, at a moment of maximum jeopardy for the Allies.                                                                            　　In the famous words of Field Marshal Haig, they had their "backs to the wall" as a great German attack swept westward in a final bid to win the bloodi..