Who are the great generals?

[Rifleman]

.....introduction of open battle order (the version of that period).....came after the USCW.

I will disagree with this one part of your post, Fuchs.

Open battle order with firearms started to appear on the North American Continent during the colonial era. Admittedly, at that time it was practiced by scouts and skirmishers, not the line infantry.

The German Jagers made contributions to the evolution of open order tactics in the American Revolution, credit given where due.

The green coated US Rifle Regiment was very active on the frontier and in the War of 1812.

The famous Baker rifle armed British rifle units of the Napoleonic era were refinements of the 60th Regiment of Foot, aka The Royal Americans, who learned their trade on the North American frontier.

The USA fielded two green coated sharpshooter regiments during the Civil War. The CSA fielded many sharpshooter battalions. Both units continued to develop open order light infantry tactics.

And finally, the true sniper did not emerge in the trenches of WWI as an outgrowth of the earlier skirmisher. Nor can the Boers take credit. The true sniper emerged on the Civil War battlefield as an independent Confederate sharpshooter (the word sniper was not known and used) with a British Whitworth target rifle brought in by blockade runners.