The second reading, Sheni, of Mattot is about the war with Midian, the Moshe's final battle:
נְקֹ֗ם נִקְמַת֙ בְּנֵ֣י יִשְׂרָאֵ֔ל מֵאֵ֖ת הַמִּדְיָנִ֑ים אַחַ֖ר תֵּֽאָסֵ֥ף אֶל עַמֶּֽיךָ.
Take the revenge of Bnei Yisrael on Midian, and then you will pass away.
It is also the last war before the people enter the land of Israel. This battle is unique, as up to now the Torah doesn’t give us details of the fighting force, but here we are told
אֶ֚לֶף לַמַּטֶּ֔ה אֶ֖לֶף לַמַּטֶּ֑ה לְכֹל֙ מַטּ֣וֹת יִשְׂרָאֵ֔ל תִּשְׁלְח֖וּ לַצָּבָֽא.
Each tribe shall send a thousand men to the army.
Despite the census we read about last week, each tribe, big or small, sends the same number – both Shimon with 22,000 men and Yehuda with 75,000 had to rally one thousand men each for the army.