I tried it by the sea route – absolute nightmare.
An endless spam of enemy ships was too much for my 35 Galleons.
The land route is far easier.
Kill the bandits, forget about the sea and boom into Elephant + Arbalester.
Those two units are enough if you micro the Arbs and attack move the Elephants.
It’s a good idea, when you enter the city, to conquer a couple of flags so that enemies don’t spawn from your back, and your forward Stables/Ranges can replenish the inevitable losses on your push.
Elephants tank a ton of damage, and you should prioritise killing Onagers who shred your Arbs.
I won it a the 4th-5th trial with barely a minute left, but I know my execution is far from perfect.
Anyone more skilled than me will carry this out much better