Voting to support troops thrown into combat is in NO WAY voting to support a war:

...Again, it is a singular omission in this message, that it, no where intimates when the President expects the war to terminate. At it's beginning, Genl. Scott was, by this same President, driven into disfavor, if not disgrace, for intimating that peace could not be conquered in less than three or four months. But now, at the end of about twenty months, during which time our arms have given us the most splendid successes--every department, and every part, land and water, officers and privates, regulars and volunteers, doing all that men could do, and hundreds of things which it had ever before been thought men could not do,--after all this, this same President gives us a long message, without showing us, that, as to the end, he himself, has, even an imaginary conception. As I have before said, he knows not where he is. He is a bewildered, confounded, and miserably perplexed man. God grant he may be able to show, there is not something about his conscious, more painful than all his mental perplexity!
                         --Abraham Lincoln, Speech in House of      
                         Representatives, January 12, 1848   

...Allow the President to invade a neighboring nation whenever he shall deem it necessary to repel an invasion, and you allow him to do so whenever he may choose to say he deems it necessary for such purpose, and you allow him to make war at pleasure. Study to see if you can fix any limit to his power in this respect, after having given him so much as you propose. If to-day he should choose to say he thinks it necessary to invade Canada to prevent the British from invading us, how could you stop him? You may say to him,--I see no probability of the British invading us"; but he will say to you, "Be silent: I see it, if you don't."

The provision of the Constitution giving the war making power to Congress was dictated, as I understand it, by the following reasons: kings had always been involving and impoverishing their people in wars, pretending generally, if not always, that the good of the people was the object. This our convention understood to be the most oppressive of all kingly oppressions, and they resolved to so frame the Constitution that no one man should hold the power of bringing this oppression upon us. But your view destroys the whole matter, and places our President where kings have always stood.
                         --Abraham Lincoln, Letter to Herndon,
                            February 15, 1848

...I do not mean to do anything with Mr. Ficklin, except to present his face and tell you that he personally knows it to be a lie! He was a member of Congress at the only time I was in Congress, and [Ficklin] knows that whenever there was an attempt to procure a vote of mine which would indorse the origin and justice of the war, I refused to give such indorsement, and voted against it; but I never voted against the supplies for the army, and he knows, as well as Judge Douglas, that whenever a dollar was asked, by way of compensation or otherwise, for the benefit of the soldiers, I gave all the votes that Ficklin or Douglas did, and perhaps more.        
Mr. FICKLIN: My friends, I wish to say this in reference to the matter. Mr. Lincoln and myself are just as good personal friends as Judge Douglas and myself. In reference to this Mexican War, my recollection is that when Ashmun's resolution [amendment] was offered by Mr. Ashmun of Massachusetts, in which he declared that the Mexican War was unnecessarily and unconstitutionally commenced by the President—my recollection is that Mr. Lincoln voted for that resolution.        
Mr. LINCOLN: That is the truth. Now, you all remember that was a resolution censuring the President for the manner in which the war was begun. You know they have charged that I voted against the supplies, by which I starved the soldiers who were out fighting the battles of their country. I say that Ficklin knows it is false. When that charge was brought forward by the Chicago Times, the Springfield Register [Douglas organ] reminded the Times that the charge really applied to John Henry; and I do know that John Henry is now making speeches and fiercely battling for Judge Douglas. If the Judge now says that he offers this as a sort of a set-off to what I said to-day in reference to Trumbull's charge, then I remind him that he made this charge before I said a word about Trumbull's. He brought this forward at Ottawa, the first time we met face to face; and in the opening speech that Judge Douglas made, he attacked me in regard to a matter ten years old....
                --Lincoln-Douglas Debate at Charleston, IL, September
                   18, 1858