These sections are from The Tree of Battles of Honoré Bonet, translated by G.W. Coopland (Liverpool: Liverpool University Press, 1949).

Chapter 68: If a man is a citizen of two cities which are at war, which of the two must he assist?

What shall we say in the case of the a citizen of Ghent who has a house, goods, clothes, and many other possessions, in the city of Bruges, and who is accustomed to dwell part of the year in one of these towns and the rest of the year in the other, and who has been accepted as a citizen by each; if it should happen that they are at war, which of the two should he help?  I reply that he is bound to go to the help of the first, that is to say, of that one of the two towns in which he was first received as citizen, and this for the reasons declared in the previous discussion [Chapter 67 - for knights, they should help the lord that they first swore an oath to, and if possible, send a replacement to the other lord].

Chapter 69: Whether a Serf can be compelled to follow war at the command of his lord.

We must next consider whether men in state of serfdom can be constrained by their lord to go to battle or war at his pleasure.  I reply that they can, for they are bound to do their lord's will and obey it (although there are few people of this sort in France, but many in Lombardy and Aragon.)

            There is another kind of servitude called libertine serfdom, which involves obligations to perform certain tasks in the fields: for instance in the corn fields or vineyards.  Such serfs would not be required to take part in war, for, considering the nature of their state, a new servitude cannot be imposed on them.

Chapter 70: What persons cannot and must not be compelled to go to war.

Further, there are other people who cannot be compelled to go to battle and war, such as old men, the sick, the deaf and the blind, or those who are too young to bear harness, and such like people.  But if a man were wise in counsel I hold that his lord could constrain him.  In case of a dumb man, although he cannot speak, yet if he is valiant and strong in body I should say that he could be constrained, if it pleased his lord.  But women should not be compelled to go to war, even though they were wise, rich and strong.  As for service by substitute, I do not say that they are not bound to it.