Age of Empires II: Definitive Edition

Rajendra Campaign, Mission 4.

The key to this is speed and saving your trade cogs!
Big tip from THE DEADLY DOG, spread a chain of the special ships along so your trade cog can travel safely to each dock.

The mission ends as soon as you destroy the 3 castles, I didn't bother attacking the wonder because the villagers quit building it to go garrison in the castles which I destroyed.
Enemy boats spawn when your trade cogs spawn, so even if you think you cleared the passage, you didn't. Send some boats back to the trade cog spawn point to escort them to each new dock that you get.
Build at least 5 more of the unique boat units! They are very valuable in this mission for tanking and killing boats.
(Remember, when the city's switch control, you can't build any more units in that city! You can however build every unit in the final area you get)

Each city switches control as soon as you leave it, as well as Kalenga switching to enemy once--when Kalenga switch to enemy, charge the gates again immediately to kill the units defending and you'll get ally status again.

Once you gain the final general's army, take the scouts and send them NW of the green city to find 3 trebuchets--you can use these to take out one castle on their own.

After leaving the blue city and recapturing it, take a small squad of troops(20 should be enough) and go north to raid the markets of the villages for bonus food.

Use the market in blue while you can--enemy units will target it to prevent you trading.

And again, SPEED to the general. Rush the city gates at each city, try to get a unit on Stand Ground in each gate so your troops can rush through and kill the rest of the defenders.

Once you reach the general, after some dialog, a 5 minute timer will start. You can wait or not, doesn't really matter, just check what the wonder build status is. I waited for them to attack while I was researching upgrades and spamming units up to pop cap.

If you've done it all well, the wonder shouldn't be much more than half, you should be near max pop, your trade cogs have been escorted and arrived, and you have the trebuchets ready to go.

Wait for yellow or don't wait, just put your troops in position and charge for a messy battle!

Don't forget to heal during the battle!

Kill the 3 castles with Armored Elephants(Trebs can get one before they self-destruct)

And win.