Sequence 10 - Force Najeure / An Unpleasant Turn of Events
Messenger will bring a news that Antonio wants to see you.  Of course, go to his villa.  After the conversation go to military district and talk with your potential ally.
Sequence 10 - Caged Fighter
You will find a wounded soldier there, who will send you to another place.  Jump on the roof and go there. 
Go north until you will reach the water - you will find many guards here. Two of them are attacking from the chimney.  The third one is located a little farther, so throw him into the water. D'Alviano is in the cage. 
Jump on two guards and kill them.  The next two you have to murder in combat. Later you can free the prisoner. 
Jump on two guards and kill them.  Run with a new companion to the city and try to avoid guards. 
You will see a bigger groups of guards near your target - of course you can kill them. Fight with two soldiers and their captain.  Open the gate and then enter the courtyard.  Then talk with your new companion.
Sequence 10 - Leave No Man Behind
Your task is to free some mercenaries. Go to the appropriate place - you will find more large cages there.  Climbs onto the roof and remove guards near the door. 
Release mercenaries - some of them will decide to join us. Move with them along the shore to the another prison. When you will be close send them to fight with the enemy patrol.  Climb on the building and move close to the water - eliminate two enemies that are standing near the tree. 
Now, help your subordinates to deal with the army  and release another group of prisoners. Your troops will be much more numerous now - o with them to the last prison. There, eliminate all enemies and free the rest of mercenaries. 
Sequence 10 - Assume the Position
Return to the leader.  He will present his attack plan. First, go with a group of mercenaries and eliminate four enemies. 
Enter the alley - a few warriors will wait for a signal here.  With the rest of them run to the second point, and do the same - finish off your enemies and talk to your inferiors. 
The third point is located near the doctor.  Kill all enemies and replace them with your guards.  Sequence D'Alviano.
Sequence 10 - Two Birds, One Blade
You need to give a signal to all soldiers, so go to the highest tower in the area.  Use wooden stairs to get to the top. 
D'Alviano will need your help - jump down into the water.  Here, kill two enemies in heavy armors.  Just dodge the blows and then attack.
Now it is time to chase Dante, who is fleeing to the Templars hideout. From the roof you will see that there is a bloody fight down there.  Jump down and kill all enemies. 
Now you have to fight with Dante - it will be enough to dodge his blows and counterattack.  At the end you have to stop two fleeing Templars. You can kill them in a standard way and then deal with other soldiers. However, there is a better way to do it - they are running to the vessel, so instead of chasing them jump into the water.  Go to the second ship.
Proper ship could be recognized by the ladder. Get close to it and stand in the middle.  If you were fast, few seconds will pass before your targets will appear. Kill them fast.