The Storm of Steel was a campaign that ran from April to September 1871, primarily in Belgium and the Low Countries in Western Europe, but with associated battles in the English Channel and North Sea. Additionally, conflict arose in the South of England proper. The campaign was noted its large-scale, grinding armoured warfare across the low countries.
The Kingdom of Britannia, in association with their allies the Kingdom of Belgium and a Russo-Polish expeditionary force, launched a full-scale assault to take areas of the Protectorate of Belgium and locations along the Scheldt estuary, to prevent the Prussian Empire from using the ports in the area to launch another direct attack on the English mainland.
The assault did make headway across Belgium, including a memorable Britannian victory at the Second Battle of Waterloo. However, the assault eventually wound down as the Grand Coalition attempted to move across the Scheldt and into the Netherlands.
Additionally, the Republique of France launched an ambitious amphibious assault (in reality a large raid) on southern England. The French forces managed to create a beach head and strike towards Kent, but eventually fell back and withdrew his troops in good order.