George,
The call for the 75,000 is an important reason Arkansas, went Confederacy. The response of Rector to Lincoln is classic. He told Lincoln in no certain terms Arkansas would not be sending troops to put down the Rebellion, at that point put Arkansas in a State of Rebellion, whether it wanted to be or not. The Delegates to The first Secession Convention from Lawrence County described themselves as "anti immediate Secessionist."
However, when the 2nd convention was convened they were fire eaters. they were incensed at the call by Lincoln. Milton Baber was an attorney from Smithville, but his wife's family were plantation owners and had several slaves. Baber, apparently put his heart into his words because he served in the 7th Arkansas as a Lieutenant and a Captain, was pulled by Shaver to be a Major and Lt. Colonel in the 38th Arkansas, and then colonel of the 45th. Samuel Robinson was a plantation owner in Clover Bend area, and slave owner. Several of the surrounding counties were anti-succession at first convention, but were all for it. Lincoln's call for troops had a huge effect for the Confederate cause in Arkansas.
Whether or not the South, previously really expected or wanted an all out war, it became immaterial with that call by Lincoln. Southerner's knew at that point Lincoln was serious about war. At that point, and instead of sending fear, and nudging Southern States still in the Union, to stay in the union, it backfired. Arkansas, especially Lawrence, Randolph County had many war of 1812 and Mexican War veterans, who did not take kindly to what they viewed as a threat. Like it or not, Arkansas was closely tied with Texas, Louisiana, Tennessee, Virginia, North Carolina and Missouri by family and by economics. They would go which ever the sister states went.

I cannot speak of the other Southern States, but Lincoln's proclamation, and the sending of the Star of the West, drove Arkansas to War. I do not care, what documents, from the Convention, and statements of Arkansas politicians before the War, those are words spoken in the moment. The actions are what speaks the loudest here. Arkansas did not go to War for Slavery. A huge and very credible argument can be made, that the State Chose to survive by throwing in with the Confederacy. If Arkansas had remained in the Union, the State would have been quickly subdued by the neighboring States. With the Confederacy, Arkansas leaders thought they only had to worry about one State, Missouri. Arkansas leaders knew any invasion from the North would occur from Missouri, and they felt confident that Arkansas Militarily by itself could protect the Northern Border with Missouri. Especially with having only two major roads into Arkansas, one in Northwest Arkansas, and Northeast Arkansas. Arkansas could not imagine all of her Military Force and equipment, and the best of the best would be sent out of Arkansas. the 1st and 3rd Infantry to the Army of Northern Virginia, and the rest to form a part of the Confederate Army of Tennessee. AR Anyway you view it, Arkansas was in a "no win" situation. Arkansas did not even have a bench, let alone a 2nd string team, when the 1st string team was pulled. Arkansas saw the reverse was true if she had stayed with the union, her manpower would be pulled North leaving Arkansas unprotected.