I had a quick look in this section and the new arrivals guides section, and did not see anything on this. If it already exists, then I apologise in advance. My decision to create this guide was prompted by this thread by a user unfamiliar with the interface.
Divisions are a powerful tool that exists in World of Warships, and functions very much like a platoon in World of Tanks (and squadrons in World of Warplanes). They allow 2-3 players to group up as a team, and enter battle with each other together. Much like platoons in World of Tanks, the play of a division within a team can swing the tide of a battle one way or another. So lets get on with this.
First things first - How do I create a division? Unlike World of Tanks, currently you cannot create an empty division (to the best of my knowledge). Creating a division is simple, and 2 options exist both of which establish a division upon the sending of an invite.
Option 1 - Contacts list. If you view your contacts list, you have the option to add someone to your division as shown in the image below. All you have to do is click on the circled button and it will send a division invite to your contact.
Option 2 - Looking for a division list. This list is populated by anyone on the server who indicates their status as "Looking for a division". This status is set by clicking the Create Division button at the top next to battle and choosing the enlist me in a division option. If you wish to add a member from this list to your division you create, all you need to do is double-click their name. As a warning though, adding yourself to this list by selecting Enlist me in a division can result in getting invites from anyone.
What if I want more than 1 other person? Well that's easy to do. You can follow either of the options above to invite someone (they still work so long as you have an empty spot), or you can click the invite player button and invite someone from the Option 2 list aswell.
If I'm joining someone else's division, how do I do it? If you receive an invite, you will get a screen similar to the one shown below if you are on the port home screen. All you need to do is click accept to join the division. If you are not on the port screen, you will still get a notification in the bottom right corner of your game window. Do note, you only have 5 minutes to accept the invite
What if I invited the wrong person and wish to correct my error, or decided that I didn't like someone who was in my division? As a division leader, and option exists to remove a member from your division. It can be found to the right hand side of the member's name in the division window and is only visible to the leader. The leader can remove anyone at any time by clicking the "X" (Whether it's just sent an invite, or already accepted the invite).
Now that I have my division, how does it work? Well simple. You select the ship you want to play and click the ready button. You can toggle this at any time by clicking the obverse to whatever is selected (works like the buttons for auto resupply) as seen in the image below. Divisions, like platoons in World of Tanks, operate matchmaker based off the highest tier/bracket in your division. This means that it is highly recommended that you play the same tier or +-1 at the most, as otherwise you could get into matches you wouldn't normally see and could severely hamper your team's efforts to win. Matchmaker does not compensate your team for an ill-formed division. There is however 1 restriction placed upon divisions - You can only have 1 Aircraft Carrier within a division at any given time. Unfortunately I do not have any CVs yet, so was not able to screenshot the warning message.
So how do we join a battle? Once all players are ready, indicated by all players having a ship showing in the left bar and generally confirmed before launching, the division leader can click battle to throw your division into a match.
In battle, the first thing you will notice is that your division members all get assigned a random division number (unique to each team) based off how many divisions exist on the team. Those of you who play other Wargaming titles may be familiar with this, but an example of this can be found below.
Can I see my division mates easier in game so we can group up? Well yes. In addition to the numbers, on the team list, main view, and minimap your division members will have orange icons and names instead of the default green/grey. This is done so that you can easily see where your division members are and can coordinate more easily.
How do I leave a division? Now after a long session of divisioning, you decide you want to leave. Regardless of whether you are the division leader or not, you can leave the division at any time from the port screen - if you are the leader, one of the remaining members will subsequently be assigned leader and the division can continue to operate. To leave the division 2 options exist, and these are clicking the "X" in the top right of the division window shown below or right clicking the division window in the header. Regardless of which method you use, confirmation will be requested to leave the division.
Now I know there's a lot of screenshots, but I'm hoping this helps some users not familiar with the ships interface to figure out this valuable part of World of Warships gameplay.
Thanks for reading, and if noone looks at this at least it's there for new people if they need it.