He proclaimed that those who were building houses, or were just married, or were planting vineyards, and those who were afraid, could each return to his home, according to the law.This is clearly a reference to Deut. 5-8, exempting such people from fighting in a war. However, in Sotah (44a-b), it is clear that this exemption only applies to an optional war. In an obligatory war, everyone must fight (even a groom and bride - link). This seems to contradict the evidence in the book of Maccabees.
Click here to read moreThe Sefer Ha-Chinukh (425, 528) writes that the commandments to destroy the seven Canaanite nations apply to each individual. Anyone, in the times when fulfilling these commandments was possible, who has the opportunity to kill such a person and does not do so violates these commandments, under the condition that he can do so without endangering himself. As the Minchas Chinukh points out, this condition is puzzling. Any war involves danger. If we take this condition at face value, a Jewish army would never be able to fight because that would endanger the soldiers.
R. Shlomo Goren (Toras Ha-Mo'adim, pp. 179-202) explains that there are two obligations to wage war -- a communal and a personal obligation. When a king leads the community into battle, there is a general obligation that overrides concerns of danger. An individual's personal obligation to wage war, however, is deferred by danger. No individual obligation, other than the "big three," can override personal danger. When the Sefer Ha-Chinukh said that danger overrides the obligation to destroy the seven nations, he was referring to cases where the communal obligation does not apply and only the personal obligation applies -- such as when an individual comes across a person from those seven nations.
Similarly, R. Goren suggests, the exemptions of the groom etc. do not apply to an obligatory war only if it is a communal war. When a Jewish king gathers his army to protect the Land of Israel, the entire community is obligated to fight in that war regardless of personal considerations. However, in the (early) times of the Maccabees, there was no king. The army was a group of individuals. If that is the case, then the exemptions still applied and Judah Maccabee was correct in calling such people to leave the army.