Milestones on the Road to Pearl Harbor

On December 7th, the United States will once again commemorate the anniversary of the tragic attack on the Pearl Harbor naval base. Seventy-six years ago, the nation experienced a terrifying day when a fleet of Japanese fighters and bombers flew into Oahu airspace. The attack that followed left over 2,400 American servicemen and civilians dead. The anniversary of the attack is used to memorialize those lost during the assault and recognize the survivors who went on to fight in the war that ensued.

Before Pearl Harbor was attacked, a series of events unfolded in the months prior to the "date that [would] live in infamy," warnings and movements from across the Pacific that would ultimately culminate in the devastating assault. Here are some of the lesser known milestones on the road to Pearl Harbor.

The Pearl Harbor Timeline

As the year 1941 began, tensions between the United States and Japan were on the rise. The Japanese felt that US meddling in its affairs in the Pacific and Indochina was becoming unbearable, and the proud Empire began preparing to do what it had to in order to maintain its supremacy.

January

In January of 1941, 12 months before the attack, Admiral Isoroku Yamamoto began discussions with leading Japanese officers about an attack on Pearl Harbor. At this point, an attack was simply a concept that the admiral would eventually flesh out into a deadly plan of action.

January 27, 1941: It didn’t take long for the United States to receive word of a possible attack on Pearl Harbor. The American Ambassador to Japan, Joseph Grew, wired Washington on this day to warn of the possible attack. Unfortunately, Grew's warning falls on deaf ears as American officials believed Manila, in the US-controlled Philippines, would be the primary target.

February

Adm. Husband E. Kimmel

Admiral Husband E. Kimmel is given command of the Pacific Fleet, a position he would end up not holding for long. Shortly after taking command, Kimmel requested better defense of the Hawaiian Islands.

April

American cryptographers use a project known as "Magic" to decipher Japanese diplomatic messages encoded using their Purple machine. The information uncovered isn’t all shared with the commanders with the greatest need to know, including the newly-appointed Kimmel.

May

Admiral Naokuni Nomura discovers that the United States is privy to Japanese intelligence. Despite his warning, higher command refuses to believe that the code was broken and opts to keep it the same.

July

Mock-up used in planning the Pearl Harbor attack

Admiral Yamamoto puts the final touches on his plan to attack. Japan is now firmly on the road to Pearl Harbor. He starts to train his forces to prep them for the lengthy journey and the delicate nature of the surprise attack.

September

Despite deciphering a message from Japanese naval intelligence to Japan’s consul general in Honolulu requesting a grid of the Pearl Harbor naval base, American intelligence fails to share the message with Kimmel. The transmission asked for information regarding the placement of each ship within the harbor.

November

A special envoy is sent to Washington by the Japanese to try and come to a diplomatic resolution. None is ultimately found.

November 16, 1941: Japanese submarines depart for the long journey across the Pacific. They become the first foreign vessels to enter the waters off the coast of Oahu.

November 26, 1941: The 1st Air Fleet, known as Kido Butai or Mobile Force, departs Japan and begins its trek on the road to Pearl Harbor

November 27, 1941: Kimmel and General Walter Short receive a “war warning” from Washington that suggests a Japanese attack may be imminent. It doesn’t pinpoint Pearl Harbor, but warns that the target would be an American asset in the Pacific.

December

Pearl Harbor seen from a Japanese attack plane

December 6 and December 7, 1941: The Japanese striking force reaches its destination. American intelligence decodes a message that pegs Sunday, December 7th as a deadline for an action. Four hours before the attack, the message is delivered to Washington but isn’t forwarded to Pearl Harbor until after the attack begins.

December 8, 1941: In shock from the deadly attack, the United States struggles to find a response. In Congress, President Franklin D. Roosevelt delivers an impassioned speech that leads to a nearly unanimous vote to declare war on Japan.