"The decision to send the nation to war is perhaps Congress’s gravest responsibility, and in the House war votes can be solemn, weighty occasions. For the Members, to declare war against a foreign power is to send their constituents, their neighbors, their family, and even themselves into harm’s way."
https://history.house.gov/Institution/Origins-Development/War-Powers/
"The last time the United States Congress met its constitutional mandate officially to declare war by deliberating and voting for the record to engage members of the U.S. military, each of whom takes an oath to protect and defend the U.S. Constitution, was 76 years ago, in 1942."
https://civcm.psu.edu/constitution-day/constitution-day-2018/when-did-congress-last-declare-war
"The Constitution’s Article I, Section 8 specifically lists as a power of Congress the power “to declare War,” which unquestionably gives the legislature the power to initiate hostilities. The extent to which this clause limits the President’s ability to use military force without Congress’s affirmative approval remains highly contested.
Most people agree, at minimum, that the Declare War Clause grants Congress an exclusive power. That is, Presidents cannot, on their own authority, declare war."
https://constitutioncenter.org/interactive-constitution/interpretation/article-i/clauses/753
"What’s fascinating is how virtually no one, except libertarians, brings up the U.S. Constitution when it comes to foreign wars, specifically that part that prohibits the president from waging war without a congressional declaration of war."
"The Constitution is the highest law of the land. It embodies the constraints on federal power that were imposed on the federal government as a condition of permitting the federal government to come into existence. The Constitution is the law that we the people have imposed on federal officials, including the president and his military and paramilitary forces. Just as federal officials require us, the citizenry, to obey laws that they impose on us, they are required to comply with the law that we have imposed on them.
The Constitution requires a congressional declaration of war before the president can wage war"
https://www.fff.org/2011/03/17/constitution-requires-congressional-declaration-war-libya/
"No president can be allowed to ignore the constitutional power of the U.S. Congress to declare war. No Congress can evade its responsibility to take a public position – and having just four senators and four representatives act on behalf of all the others is the worst kind of evasion of responsibility. The Founders wrote Article I, Section 8 because they understood that a declaration of war was the most serious responsibility. The Congress must recover its constitutional power and responsibility."
https://www.americanthinker.com/articles/2015/11/we_need_a_congressional_declaration_of_war.html
"Although U.S. troops have gone to war many times since 1776, Congress has only declared war 11 times."
http://outsidethewire.armytimes.com/2014/06/17/how-many-times-has-the-u-s-declared-war-see-all-11-declarations/