The lesson of history is that vigilance must be eternal

Regular air attacks on Darwin continued until November 1943, with 64 raids on Darwin and 33 on other places in Northern Australia including Townsville, Derby and Port Hedland.

The death toll from these attacks reached more than 900 people, with numerous ships and almost 80 aircraft destroyed.

It is estimated that the Japanese airforce lost more than 130 planes during these raids.

At that time there was great fear in Australia that the Japanese bombing was preparing the way for a ground invasion.

Japan had officially entered World War II in December 1941 and quickly achieved a number of decisive victories including at Singapore only a few days prior to the first attack on Darwin.

Australia's northern defences were quickly bolstered to prevent such an invasion.

These defensive measures included a large increase in the numbers of troops stationed in the city.

Soldier numbers peaked at 110,000 in 1943.

My father Douglas Bishop was among those who served in the AIF in Darwin during the war.

He returned to Darwin this week to attend the Bombing of Darwin memorial services honouring those who had served and those who had lost their lives.

It was the first time he had attended these ceremonies to mark what is now an annual day of observance.

Like many of the former servicemen and women in attendance, he found it an emotional experience.