How would the outlook of WWI and the future have been if Gen Douglas Haig hadn't authorized the disasterous Somme Campaign that wiped out the best and brightest soldiers from the British Units? I think with those soldiers who were saved from a certain death, Britain could have continued their tank program unimpeded and launced a campaign in 1917 or even 1918 with tanks used as shields to screen Allied advances. Plus the staggering loses played a huge part in anti-war sentiments that had a dramatic effect in weak, vasilating PM's like Chamberlain giving Hitler Czerslovakia and the British fighting spirits in France in 1940 that broke rather easily.