First and foremost, scout the city! If there are troops in the city you are planning to siege, make sure you send armies to remove them first, or ask others for help in removing them. Share the scout report with anyone who is helping if need be.
No catapults? No problem! All you need is 1 commander and 1 soldier (of any type), and the Siege Encampment Research completed.
Now, view the city you are going to siege in the World Map.
Next, cleft click the city, and choose 'Send Army'.
In the drop down menu, select 'Siege'.
In the expanded view, set the length of time to the max (to be on the safe side). ie, 14 days, 23 hours, 59 minutes. Also, in the lower view of the city, click an adjacent tile around the outside of the city. A red circle and arrow will appear. Click the red 'Send' button.
Once you have sent, you can view your army marching to the city in the
http://elgea.illyriad.co.uk/#/Military/Movements screen.
Once your army lands to the specified tile, it takes 12 hours for them to set up and for the fun to start! In the meantime, a second player will send their army WITH catapults to the city, but land on a separate tile. Once this second army arrives and after the initial 12 hour setup is over, you will be able to see the population of the city under siege start to drop in the Military Movements page, in the
http://elgea.illyriad.co.uk/#/Military/Sieges tab. This screen will tell you the required population and where the city is currently. Once it reaches the target population, a red button will appear in this screen that says "Storm and Capture". Once clicked, your army will enter the city and after a few minutes, the city will become yours.
In the city you sent your siege army
from, create a Messenger.
Then, once again, view your newly acquired city in the World Map, left click it, and select "Send Diplomats". Locate the Messenger you created, and click send.
Once your Messenger arrives, he will die from exhaustion, and your original sieging army will return to the city it was dispatched from.
There are 2 very important things that need to happen when sieging a city in this manner.
1. Travel time to siege the city. You MUST land at the city prior to the second army landing. Report this information to the person or people helping you.
2. Your army must be the ONLY army on the tile. The second army must be on a separate tile. Report the tile coordinates to the person or people who are helping you.