Complex sentence: In 1896 and 1897, France and Russia, technically allies, started to build large, fast armoured cruisers which outclassed all others afloat, which could threaten trade routes, work closely with a battleship fleet and in some circumstances could even confront a battleship.
Split into simpler sentences: In 1896 and 1897, France and Russia, technically allies, started to build large, fast armoured cruisers which outclassed all others afloat. These could threaten trade routes, work closely with a battleship fleet and, in some circumstances, could even confront a battleship.