Defense Options

It is important that you have thought about what you intend to do if someone else ever sends an attacking march on you.  You may not have long to respond in the event of being attacked, and will need to think and act quickly to avoid being hit, or to avoid suffering too much damage.  Some options are outlined here for consideration.
 
Defense Boosts
These are available for purchase in the alliance store with loyalty points, or in items with gold.  They will provide extra defense protection for your troops.
 
Shields
These are also available for purchase in the alliance store or in items, and once activated, means that your Stronghold cannot be attacked for a certain period of time.  However, if you have another player's reinforcing troops in your city, you will be unable to activate a shield until you have sent their reinforcements home.  You will also be unable to activate your shield whilst reinforcing troops are marching towards your city.
 
Seeking Protection within a Shielded City
Once a fellow alliance member has an active shield protecting their Stronghold, you can send reinforcing troops to their Stronghold for protection under their shield.  However, you cannot send your hero, who will remain in your city and potentially vulnerable to attack.
 
Fake Rallies
Leading or joining a fake rally protects your rallied troops from being damaged from an incoming attack.  You can pick a dead target on the map and set a long time until march (8 hours).  If you initiate the fake rally, always advise others in Alliance Chat that you are doing so, and include your hero in the rally.  Others can join your fake rally which will also protect the troops they send from any incoming attack, but they cannot send their hero to a rally, which leaves them potentially vulnerable to attack back in their own city.
 
Losses
It is important that you attempt to have sufficient hospitals to heal the amount of troops you have, although this may not always be possible.  If you do have sufficient hospitals, it is unlikely your troops will die, rather you can heal them in your hospital.
 
Unless you have an active shield, an incoming attack may reduce or totally destroy your wall traps, and reduce your resource balances.  However if you have taken defensive measures to protect your hero and troops, losing wall traps and resources is the most losses you will suffer in the attack.