My understanding is that cigarette smoking reached epidemic levels among men for the first time during this conflict, in fact the British army sold tobacco bonds for the troops at home to gain money for the vile product.
Where would we be today without this - well obviously alot more people alive, it's one legacy amongst others from that madness that still haunts us, perhaps even more then the middle east, Yougoslavia and Ireland all of whom had their borders established by it!
Of course people were encouraged to smoke then because it was considered healthy, especially for the lungs!
It took until Ed Murrow to prove otherwise on a grand scale!
No doubt some enterprising capitalist scumbags would have found away to get people addicted on a grand scale anyway.
By the way, I regard smoking as a personal choice, just don't do it in my face and there is an element of taxes on it being a tax on idiocy!