[douglas]

No, I don't think combat matters for that. There is, however, a critical difference between the move and seek after orders.

Move to planet X, Load Troops, Move to Planet Y:
Moves to planet X, attempts to load troops from enemy planet and fails
Combat occurs at end of day, planet is captured.
Load troops order has already been cleared from the queue, so move to planet Y without loading troops.

Attack planet X, Load Troops, Attack planet Y:
"Seeks after" planet X. This order remains valid even after arrival, though it no longer takes movement points to execute. The attack order takes up the entire allotment of orders for that day as it is repeatedly executed to no effect.
Combat occurs at end of day, planet is captured.
Attack order is checked and found to no longer be valid because the target is owned by the same player. Attack order is cleared and Load Troops gets executed successfully from the newly conquered planet. Start seeking after planet Y.

Edit: hmm, I haven't tested this, but this might work for those cases when you can't see the target planet to give an attack order. Try giving the load troops order 11 or 12 times after the move to planet order and before moving to the next planet. If the number of orders a planet can execute on day 0 (21 orders) is the same as the max orders per day for a ship, the last 1 or 2 move/load troops order pairs won't be cleared on the turn combat starts and will still be in the queue the day after for when the planet has been captured. Just be sure you have enough force to capture the planet in one battle.