Correct, that is what the retreat rule says (Pacific 1940.2 page 20):
Condition B: Attacker retreats:
The attacker (never the defender) can retreat during this step. Move all attacking land
and sea units in that combat that are along the battle strip to a single adjacent friendly space
from or through which at least 1 of the original attacking land or sea units moved. In the case
of sea units, that space must have been friendly at the start of the turn. All such units must
retreat together to the same territory or sea zone, regardless of where they came from.
However as the attacker using this rule as strategy/tactic you are facing the risk that ‘Condition B’ might not occur due to the battle result (Condition A—Attacker and/or Defender Loses All Units). Also for at least one unit it is not an “additional” space - but just the space it came from before.