Sketching a world war in 1862

If a world war began in 1862, who might fight whom?

Probably Britain against France at the core, with Prussia leaning British, Spain leaning French, the United States neutral or British-aligned, and Russia uncertain.

The scenario is a diplomatic thought experiment rather than a prediction. Britain and France are the likely opposing cores, with Prussia and associated German states leaning toward Britain and Spain toward France. The United States might remain neutral or find itself aligned with Britain, while Russia is the largest wild card and might lean French. South American alignments would further complicate the map. A world war in 1862 cannot simply borrow the alliance blocks of 1914.