Defense Strategies in Mass Combat

Precis: A quick review of the ways to get a Defense Bonus in Mass Combat

In my Mass Combat game, there's been some confusion about when a force can benefit from a Defense Bonus and when it can use the various defense strategies. I was pretty confused myself, and when I went back and rechecked the rules, I realized I was confused because the conditions are pretty confusing. So I want to write about all the conditions and what they require.

Mass Combat distinguishes between pitched and encounter battles, and mobile, encamped, and bunkered forces. As an additional complication, a force can be surprised or ambushed. How does all that effect available battle strategies?

Battle Type	Force Condition	Available Strategies	Defense Bonus	House Rule Defense Bonus
Encounter	Mobile	Any but Deliberate Attack or Deliberate Retreat No defenses except Mobile Defense on 1st round; No retreat strategies on 1st round		No
Encounter	Encamped	Any but Deliberate Attack or Deliberate Retreat	Can't get DB	Yes
Encounter	Bunkered	Any but Deliberate Attack or Deliberate Retreat	Can get DB	Yes
Pitched	Mobile	Any; can't choose Deliberate Defense after 1st round or at all without a DB	Can get DB with initiative	With iniative
Pitched	Encamped	Any; can't choose Deliberate Defense after 1st round or at all without a DB	Can get DB with initiative	Yes
Pitched	Bunkered	Any; can't choose Deliberate Defense after 1st round or at all without a DB	Can't win initiative so can't get DB	Yes
Pitched	Mobile Ambusher	Any but Defensive	Gets DB even without a defense strategy	Yes
Pitched	Mobile Ambushee	Must Rally until confusion is cleared or Full Retreat; can't choose Deliberate Attack	Lost initiative so doesn't get DB	No
Pitched	Encamped or Bunkered Ambushee	Must Rally until confusion is cleared or Full Retreat; can't choose Deliberate Attack	Lost initiative so doesn't get DB	Yes
Pitched	Besieger	Any		No
Pitched	Besieged	Any Defense except Rally, or Raid	Can't win initiative so can't get DB	Yes

This actually turned out to be more confusing than I intended. Bunkered forces can never win initiative in the Recon contest (Mass Combat 29) but that means they can never win the initiative contest and can only get a Defense Bonus if they're lucky enough to have a mobile force trip over them in a forced encounter battle. Encamped forces can win initiative and force an encounter battle, but if they do, they don't get any Defense Bonus. This makes very little sense.

I double checked the Mass Combat errata and this is apparently how the system is supposed to work, unless I'm missing something.

I think the easiest and most understandable house rule is to rule that encamped forces always get a defense bonus unless they have the No Security posture.