The setting appears prettier in 1903!
Since the monument marked the site of the Famous Debate, when Lincoln posed the historic "Dilemma Question", that two-ton stone has not likely been moved very far.

Reading some of the material supplied by Fred G., I see that, the 6th Illinois N.G. Regiment was shipped from Springfield, Ill. to Camp Alger in Northern Virginia.

They bivouacked at Camp Alger, near Washington D.C., until being transported to Santiago, Cuba, and from there to Puerto Rico.
I would hazard to guess, the 6th Illinois N.G. was issued 'Trap-Door' Springfield rifles, at Camp Alger for the Cuba Campaign. When they embarked for Puerto Rico, they likely were issued Krag magazine rifles in Cuba.

I have a paper bond book on Camp Alger, which is an interesting read. Two of the Michigan Regiments, (33rd Mich. and 34th Mich.), also were sent to Camp Alger. They had a shorter stay in Virginia and got to Cuba in time to see some action.

This interesting book has references to the 6th Illinois N.G., but not, Co. L or Simon Ottenhausen specifically.

I have attached some content for everyone's enjoyment:

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