Text in the card:
" Confederate player may move 5 SPs using Strategic Movement (rail connections only) to the same space with a Confederate General who is activated normally and must attemp to enter a space with at least one or more Union SPs or fort. If general casualty occurs in the battle caused by this card, the Commanding General is eligible, this is an exception to the rules. See 4.5"
That happens if after receiving the SPs it does not reach any SP or fort of the Union? Is it activated? Can it move? Is not it possible to play the event?
The 'attempt' must be possible otherwise it is not an attempt. So if the general is not within range of a Union force, the conditions of the event cannot be met. Under these circumstances, if the conditions cannot be met, the event cannot be played and the card is only usable as an OC play.