It started in 2011, with Libya. No, scratch that. It started in 1789, with Article I of the Constitution of the United States:

Article I
Section 1.

All legislative powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives.

Section 8.

The Congress shall have power....

To declare war, grant letters of marque and reprisal, and make rules concerning captures on land and water;

Notwithstanding the above, Obama took military action against Libya without seeking authorization from Congress, something we would probably not want should never want either Hillary or Trump any President or any other single individual to do, something the Framers expressly prevented. Several members of Congress sued.

Kucinich and Reps. Walter Jones (R-N.C.), Howard Coble (R-N.C.), John Duncan (R-Tenn.), Roscoe Bartlett (R-Md.), John Conyers (D-Mich.) Ron Paul (R-Texas), Michael Capuano (D-Mass.), Tim Johnson (R-Ill.) and Dan Burton (R-Ind.) filed the complaint Wednesday at the U.S. District Court for the District of Columbia.

“With regard to the war in Libya, we believe that the law was violated,” Kucinich said in a statement. “We have asked the courts to move to protect the American people from the results of these illegal policies.”

The House members argue that the Obama administration overstepped its constitutional authority by authorizing the use of U.S. military force abroad without first receiving approval from Congress. U.S. forces have been involved in the campaign against Libyan leader Moammar Gaddafi for 88 days.

https://www.washingtonpost.com/blogs/2chambers/post/kucinich-other-house...

It's been a while, but, IIRC, the original complaint cited both the War Powers Resolution (whose constitutionality is itself controversial, IMO) and Article I of the COTUS, but the complaint was later amended to rely solely on Article I. But, please don't hold me to that bit.

A few days after filing of the lawsuit, Nancy Pelosi, apparently under some delusion that she was the federal judge deciding the case, declared Obama did not need to consult Congress over Libya. http://www.cnsnews.com/news/article/pelosi-obama-doesnt-need-congression...

Later, the person who actually was the federal judge deciding the case dismissed the case because of standing. The court said there was no evidence that the ten members of the House who sued had authority to represent the House of Representatives: Without that authority, they were in court merely as ordinary citizens. Ordinary citizens have no standing to sue over government action that does not affect them more directly than it affects other Americans.

http://dailycaller.com/2011/10/20/judge-tosses-congressional-lawsuit-aga...

The court did not say that no member of the House could sue the President over taking military action without Congressional approval. To the contrary, the Court seemed to leave wide open the possibility that evidence of authority to speak for the House would suffice to eliminate the standing problem and allow a lawsuit against the President to go forward. IMO, the Court all but drew a map from the Capitol building to the courthouse.

Yadda, yadda, on August 20, 2012 Obama allegedly drew a red line in the sand about Syria, an implied threat of U.S. military action. http://firstread.nbcnews.com/_news/2012/08/20/13379062-obama-draws-red-l...

Congress was, I believe, then in recess, but don't hold me to that either. In any case, at some point, members of Congress were in recess, but left their home states anyway, to undertake a media blitz about taking military action against Syria without consulting Congress. They also got well over 100 other members of the House, Democrats and Republicans, to sign a letter to the effect that Obama had to consult Congress before taking military action against Syria.

“Engaging our military in Syria when no direct threat to the United States exists and without prior congressional authorization would violate the separation of powers that is clearly delineated in the Constitution,” states the letter, spearheaded by Rep. Scott Rigell (R-Va.).

http://thehill.com/blogs/blog-briefing-room/news/319127-55-house-members...

Then, Boehner who, as Speaker of the House at the time, did have the authority to, well, speak for the House, sent Obama a 14-point "legal letter," dated August 28, 2013, essentially questioning how Obama would justify taking military action in Syria without Congressional approval.

http://www.speaker.gov/press-release/boehner-seeks-answers-president-oba...

After that, Obama "backed down."

Mr. Google will quickly provide a plethora of articles citing other, non-legal reasons why Obama "blinked," about his red line in Syrian sand. However, my money is on avoiding either impeachment or a lawsuit by the U.S. House of Representatives challenging the authority of the President and Former Constitutional Lecturer to take military action without Congressional approval, as specified in Article I of the COTUS.

In any event, in 2014, the House took a general vote authorizing the House to sue the President and other members of the Executive if he or they acted acting outside Constitutional authority. At that point, it was probably unrelated to Syria, even if the Syrian incident had started wheels turning. It passed handily. http://clerk.house.gov/evs/2014/roll466.xml

I want to be clear that this is not about Alligator Ed's thread. This is in the interests of getting the above facts on record, on this board, anyway. Obama's cowardice did not keep us out of yet another Vietnam in Syria, nor did internet petitions, nor did some small, scattered demonstrations. The implied threat by the House of a lawsuit or an impeachment and the persistence of House members did that.

Knowing what worked and what didn't, even though it happened around the same time, has value Too often, we mistake correlation with causation because we have no idea what is happening behind the scenes. Even with all the above, we don't know what happened behind the scenes, say between Obama and Boehner. As always, we know only what certain people chose to make public.