Bridges on Proverbs 20:18
Charles Bridges on Proverbs 20:18

18.  Every purpose is established by counsel: and with good advice make war.
This is true wisdom — to deliberate before we act, and to establish our purpose by sound and experienced counsel. Even the wisest of men valued this strengthening resource. (1 Kings 12:6.) God has placed us in society more or less dependent upon each other. And therefore, while it is most important to possess a calm and decided judgment; it is not less so to guard against an obstinate and exclusive adherence to our own opinions. (Chapter 15:22.) Especially in the national counsels the rule is most weighty. With good advice make war. (Chapter 11:14; 24:6.) Wars for the purpose of ambition or aggrandizement can never be wisely made. Fearful may be the result of inconsiderate, self-willed measures. David took counsel of the LORD;† Nehemiah, while supporting his courage by faith,† established his purpose by counsel, and called his counsel to deliberate in all emergencies.† Ahab, asking counsel of his false prophets;† Amaziah, despising the sound counsel given to him† — both with bad advice made war to their own ruin. Even godly Josiah — making every allowance for his circumstances, was probably chargeable with precipitation; and, neglecting to establish his purpose by the counsel of the LORD’s prophets then living among his people, was chastened with temporal destruction.†
Now ponder Bishop Hall’s description of the spiritual war. ‘It admits of no intermission. It knows no night, no winter. It abides no peace, no truce. It calls us not into garrison, where we may have ease and respite, but into pitched fields continually. We see our enemies in the face always, and are always seen and assaulted; ever resisting, ever defending, receiving and returning blows. If either we be negligent or weary, we die. What other hope is there, while one fights, and the other stands still? We can never have safety and peace, but in victory. Then must our resistance be courageous and constant, when both yielding is death, and all treaties of peace mortal.’† Does not this war bring the greatest need of deliberate counsel, carefully counting the cost (Luke 14:31, 32); cleaving to our All-wise Counselor (Isaiah 9:6) and Almighty Helper? Yet fear not, under the conscious direction of his counsel, and support of his grace, to take up the song of praise — “Blessed be the LORD, my strength, which teacheth my hands to war, and my fingers to fight!” (Psalm 144:1.)