The First World War is synonymous with torrential rain, deathly deep mud and bitter cold. It seems no stalemate or major battle was without these added miseries that brought with them disproportionate infection, disease and death.

Now a new scientific study says a once-in-a-lifetime climate anomaly is to blame for the horrendous weather that contributed to hundreds of thousands of battlefield deaths and the 1918 Spanish flu (H1N1) pandemic that cost tens of millions of lives worldwide...