About how America became involved in certain wars, many conspiracy theories have been advanced—and some have been proved correct.

When James K. Polk got his declaration of war as Mexico had "shed American blood upon the American soil," Rep. Abraham Lincoln demanded to know the exact spot where it had happened.

And did the Spanish really blow up the battleship Maine in Havana Harbor, the casus belli for the Spanish-American War?

The Gulf of Tonkin Incident, involving U.S. destroyers Maddox and C. Turner Joy, remains in dispute. But charges that North Vietnamese patrol boats had attacked U.S. warships on the high seas led to the 1964 resolution authorizing the war in Vietnam.

In 2003, Americans were stampeded into backing an invasion of Iraq because Saddam Hussein had allegedly been complicit in 9/11, had weapons of mass destruction and was able to douse our East Coast with anthrax.

"(He) lied us into war because he did not have the political courage to lead us into it," said Rep. Clare Luce of Franklin D. Roosevelt, who, according to many historians, made efforts to provoke German subs into attacking U.S. warships and bring us into the European war through the "back door" of a war with Japan.

This week marks the 75th anniversary of World War II, as last month marked the 100th anniversary of World War I.

Thus, it is a good time for Eugene Windchy's "Twelve American Wars: Nine of Them Avoidable." A compelling chapter in this new book, by the author of "Tonkin Gulf," deals with how Winston Churchill, First Lord of the Admiralty, schemed to drag America into Britain's war in 1915.

In 1907, Britain launched the Lusitania, "the greyhound of the sea," the fastest passenger ship afloat. In 1913, Churchill called in the head of Cunard and said Lusitania would have to be refitted for a war he predicted would break out in September 1914.

The Lusitania, writes Windchy, was "refitted as a cargo ship with hidden compartments to hold shells and other munitions. By all accounts there were installed revolving gun mounts."

On Aug. 4, 1914, after war was declared, Lusitania went back into dry dock. More space was provided for cargo, and the vessel was now carried on Cunard's books as "an auxiliary cruiser."

Churchill visited the ship in dry dock and referred to Lusitania as "just another 45,000 tons of live bait."

When war began, German submarine captains, to save torpedoes, would surface and permit the crews of cargo ships to scramble into lifeboats, and then they would plant bombs or use gunfire to sink the vessels.

Churchill's response was to outfit merchant ships with hidden guns, order them to ram submarines, and put out "Q-ships," disguised as merchant ships, which would not expose their guns until submarines surfaced.

German naval commanders began to order submarines to sink merchant ships on sight. First Sea Lord Sir John ("Jackie") Fisher said he would have done the same.

Churchill, seeing an opportunity to bring America into Britain's war, wrote the Board of Trade: "It is most important to attract neutral shipping to our shores, in the hope especially of embroiling the United States with Germany. ... We want the traffic—the more the better—and if some of it gets into trouble, the better still."

Secretary of State William Jennings Bryan wanted to warn Americans not to travel aboard British ships. But President Woodrow Wilson, writes Windchy, "said that American citizens had a right to travel on belligerent ships with impunity, even within a war zone," a defiance of common sense and an absurd interpretation of international law.

On May 1, 1915, Lusitania set sail from New York. As Windchy writes, the ship "secretly carried munitions and Canadian troops in civilian clothes, which legally made it fair game for (German) U-boats.

"After the war, Churchill ... admitted that the Lusitania carried a 'small consignment of rifle ammunition and shrapnel shells weighing 173 tons.' New York Customs Collector Dudley Malone told President Wilson that 'practically all her cargo was contraband of various kinds.'"

Future Secretary of State Robert Lansing knew that British passenger ships carried war materiel. German diplomats in New York warned American passengers they were in danger on the Lusitania. And instead of sailing north of Ireland to Liverpool, the Lusitania sailed to the south, into waters known to be the hunting ground of German submarines.

Lusitania blew up and sank in 18 minutes. Munitions may have caused the secondary explosion when the torpedo hit. Some 1,200 people perished, including 128 Americans. America was on fire, ready for war when the next incidents occurred, as they would in 1917 with the sinking of U.S. merchant ships in similar waters.

Had Wilson publicly warned U.S. citizens not to sail on the ships of belligerent nations and forbidden U.S.-flagged merchant ships to carry contraband to nations at war, America might have stayed out of the war, which might have ended in a truce, not a German defeat.

There might have been no Adolf Hitler and no World War II.

Patrick J. Buchanan needs no introduction to VDARE.COM readers; his books State of Emergency: The Third World Invasion and Conquest of America, and Suicide of a Superpower: Will America Survive to 2025? are available from Amazon.com. Patrick J. Buchanan is the author of the new book “The Greatest Comeback: How Richard Nixon Rose From Defeat to Create the New Majority.