How mission command works: Sherman's memoirs (III) show that it is based in trust, and must work as a two-way street
Mission command is a two-way street, as is illustrated beautifully in the Civil War letters between General Grant and his subordinate, General Sherman.
The letters, reproduced in Sherman's memoirs, demonstrated how Grant communicated his intent to Sherman, then offered his suggested course of action, and finally asked Sherman for his thoughts. "In this letter," Grant wrote to Sherman upon hearing that the march across Georgia had reached the sea, "I do not intend to give you any thing like directions for future action, but will state a general idea I have, and will get your views after you have established yourself on the sea-coast."
Grant initially had some notion that Sherman might move his infantry by sea to Virginia, but Sherman really wanted to visit the hard hand of war upon South Carolina. In Georgia he had focused on seizing or destroying the property of plantation owners, but he next wanted to chastise the South Carolinians as a whole for starting the Civil War. He wrote to Grant that, "With Savannah in our possession ... we can punish South Carolina as she deserves.... I do sincerely believe that the whole of the United States, North and South, would rejoice to have this army turned loose on South Carolina." He also thought it would help increase the pressure on Lee in Virginia.
Grant, persuaded by Sherman's arguments, and his tone, agreed. "Your confidence in being able to march up and join this army pleases me, and I believe it can be done. The effect of such a campaign will be to disorganize the South, and prevent the organization of new armies from their broken fragments.... Without waiting further directions, then, you may make your preparations to start on your northern expedition without delay. Break up the railroads in South and North Carolina, and join the armies operating against Richmond as soon as you can."
Sherman's summary of mission command comes later in the book, in his conclusions about the lessons of the Civil War. It is pretty good: "When a detachment is made, the commander thereof should be informed of the object to be accomplished, and left as free as possible to execute it in his own way."