Help! Why my division suddenly stopped naval invasion and went back?

[duguseven]

My divisions successfully went across the sea and launched attack on the port, but after a few hours' attack, while they were wining, they suddenly went back with almost full organisation.
I have naval superiority when lunching the naval invasion, but lose it afterwards, I also did not assign fleet to protect the landing divisions, but it's not the first time I start a naval invasion with such conditions. I did not find any problem previously, but this time the division always went back soon after attack, even if I try to reload and delete the arrow after they start fighting.
Why? And how to prevent this from happening?

[duguseven]

And even I use Force Attack, they still withdraw from the battle and start return. Also, when going back, these divisions show a lack of supply. I not sure if supply line at sea has anything to do this.

[Mack]

Do you have the DLC that gives you the special marine/mountain/paratroop doctrine/spirits?

One of them allows Marines to withdraw, maybe that's doing something?

If you're 100% sure it's not because they de-org'd you'll probably need to post a video (at least show a picture of the battle as it's going on).

It could also be that you were defeated before additional units could reinforce into the combat, which will kill the combat and force the invasion to retreat. What is the width of your division? They should probably be 35 or less to reinforce efficiently.

If that's the case, and you have spare resources, you might want to add the radio support to the attacking units to give them a better chance to keep in the attack.

[duguseven]

Originally posted by Mack:

Do you have the DLC that gives you the special marine/mountain/paratroop doctrine/spirits?

One of them allows Marines to withdraw, maybe that's doing something?

If you're 100% sure it's not because they de-org'd you'll probably need to post a video (at least show a picture of the battle as it's going on).

I think I have the DLC, but I can't figure out the reason for them to withdraw. Yes, 100% sure it's not because of organisation. It's like a sudden forced stop, and then stay on the sea for an hour (showing red icon of supply), and start return. I even delete all assigned tasks for that general, other divisions can still proceed with naval invasion they started smoothly. Only a group of three divisions I order to attack a port always stop, then return.

I will post a pic or video on Reddit if I can't get an answer here. THX anyway.

[duguseven]

Another thing I noticed, this group of divisions, when they stopped the fight, their assigned task suddenly disappeared, left that red arrow showing no divisions assigned. Then they stay at sea for an hour without supply and start going back.
I find two other posts asking the same question, but only got a few answers asking about organisation. So I am not alone on this problem, though it rarely happens.
I played US, did hundreds of naval invasion, never had the issue.
This time, I play Australia, invading UK from my puppet Norway. Not sure it is anything to do with my puppet. Also, when the division stopped attack, there were several naval battle nearby on the sea, though I don't think they are something related.

[UTSpawn]

I think it's because they lost. Like divisions on land will stop the attack when they lose, so will amphibious.