One part of the Song of Devorah, found in this week's Haftarah, involves blessing those tribes who actively fought against Chatzor, and cursing those who did not (שופטים ה':י"ד-י"ח). At first glance, this seems fairly simple and straightforward. If one helps Am Yisrael in a time of need, one gets rewarded, and if one doesn't help, one gets punished. However, there is a problem here. Devorah actually instructs Barak to gather an army only from the tribes of Naftali and Zevulun (שם ד':ו'). While it makes sense that the other tribes who voluntarily joined the army should be blessed, one has to wonder how a tribe could get blamed for not participating in a battle if its soldiers weren't drafted.
To understand the answer, we must look into a couple of other battles described in Sefer Shofetim. In the generation before Devorah and Barak, Eretz Yisrael was occupied by Moav (עיין שם פרק ג'). In that situation, they were not liberated by an army. Rather, one man, Ehud ben-Gera, entered the palace of the King of Moav, ostensibly to present him with a gift. Ehud said he had a secret for the king, and when all of the security guards left the room, he pulled a sword out of his sleeve and assassinated the King. All Ehud needed to do was leave the palace and sound the Shofar, and an army gathered on the spot, killed 10,000 Moavite soldiers, and freed Eretz Yisrael of its occupiers. Nobody needed to be drafted into his army. Whoever heard the Shofar (which couldn't have been too many people, in the absence of microphones and amplifiers) spread the word that it was time to drive out Moav.
Now we can perhaps understand what Devorah was so upset about. The practice in that time was that if one cared about the outcome of a particular battle, but was not a part of the army, one would join the chase once his side had the enemy on the run. We see this again later in Sefer Shofetim (פרקים י"א-י"ב), with the story of Yiftach. The people of the tribe of Ephraim, whom Yiftach didn't ask to fight along with his army, get furious with him for not inviting them to fight against Amon. One would've expected Yiftach to give a response like, "I'm glad that you're so enthusiastic, but I didn't need your help." Instead, Yiftach gets furious at the people of Ephraim for not joining the battle. He says that he in fact called them, but they didn't respond. The text itself, however, gives no indication that Yiftach ever summoned the people of Ephraim to battle. Apparently, he felt that once rumors of the battle spread, they should have known to come join on their own, without a formal invitation.
The message of all of this is very clear. If the Jewish people are ever in a situation of need, one shouldn't wait for a personal invitation to help out. Whether by making Aliyah, by working for one's own community, or by helping people on an individual level, everyone must do his or her share for the group. If people choose to sit at home and do nothing on behalf of the Jewish nation, then, in the words of Devorah, "אורו ארור...כי לא באו לעזרת ה' ," "Curse them bitterly...because they did not come to the aid of Hashem" (שם ה':כ"ג).