That is the effect Jehu was seeking to bring about and that is why he wrote the letter he did. He did not want war nor was he urging them to put up resistance. Rather, he was endeavoring to strike terror into their hearts and bring them over to his side without a show of force.
How then shall we stand?
It was a good question—if the kings of Israel and of Judah had fallen before the might of Jehu, how could the nobles resist? Jehu, knowing the temper of these men, reasoned that they would not have the courage to fight. Perhaps their luxury and avarice (see Isa. 28:1-7; Hosea 7:1-6; Amos 6:4-6; Micah 2:2; 7:2-6) unnerved them for the struggle. The bold and able soldier used his wit as well as his sword.