Your timeline must be imaginary. Just because the southern states had not yet initiated hostilities doesn't mean that an armistice was in effect. That kind of agreement exists only between sovereign nations. The southern states launched their rebellion, seized federal property, fired on shipf flying the U.S. flag and you want us to believe that they were serious about negotiating a fair settlement?
So which armistice is it that Lincoln's cabinet kept insisting he was violating?