NLIKE the Americans, against which enemy the defences of the Bermuda Dockyard were built, these invaders came unseen and unannounced.

Under the cover of night or on the best Bermuda day, on the lightest of airs or coldest winter gale, their legions blew in, attacking the walls of the Land Front to the south of the Casemate Barracks.

They found the smallest chinks in the masonry armour or the minuscule plot of soil in the crevices of the natural rock and settled in for a lifelong siege. There were no explosions, no rending of the rock and masonry after the shriek of an incoming shell, no detonations from the mining of the ramparts, only a slow barely perceptible growth that could one day dash asunder the monumental defences of the Dockyard.

Evading the watchful Immigration Department, they dropped like time bombs from the bellies of passing birds, no work permits or passports needed. More than any other newcomers, these expats (some from as far away as Australasia) are destroying significant heritage at Bermuda, natural and man-made.

The two most prolific have different methods of attack. One prefers a ground level approach where it can sprawl out and kill all under the camouflage of its leafy umbrella, while the other delights in the infestation and demolition of walls, the older the better.

These aliens are the Australian casuarina and the Brazilian peppertree, "invasives" in modern conservation lingo. Perhaps due to global warming, the last decade has witnessed a spurt in the growth of this anti-Bermudian vegetation, the like of which has probably never happened before.

In the case of the peppertree, it is claimed that 25 per cent of the greenery in Bermuda is now composed of this species of tree / bush / vine (so bizarre is its unfettered growth patterns). It is claimed that the casuarina was brought in after the cedar blight in the late 1940s and it may well be that more were imported. However, photographs show casuarinas growing here early in the last century, but it is only of late years that the population has expanded so pervasively.

They have exploded with dramatic effect on nearly every historic fortification in Bermuda. Nowhere perhaps has these been more obvious than at Dockyard, but a few months ago, several things happened.

day Leslie Smith, a bus driver, came to my office at the Maritime Museum vigorously asking that we do something about the casuarinas on the walls of the Land Front at the entrance to Dockyard.

Then a few weeks later, Jim Butterfield rang to say that we had to do something about the casuarinas clambering up the walls of the museum Keep and offered to join battle with them. A few weekends later, the volunteer climbers had beaten back all the invaders at the Keep (Bermuda's largest fort) and not a moment too soon, as some of the historic stonework had already been lifted and damaged.

Those gentlemen provided the germ of an idea for a project for the Land Front, which received nods of approval from the Minister of Works & Engineering and Housing Senator David Burch and the West End Development Corporation.

On March 4, a small group of volunteers attacked the invaders on the wall face of the Land Front and on the stepped gun emplacements above. This is the first part of the historic Dockyard that everyone sees and it is now again visible.

Pitcher's Landscaping and West End Landscaping assisted the group in the removal of large casuarinas on the ditch floor of the Land Front and in chipping the cuttings into mulch. The Shell Company of Bermuda, whose territory had to be trespassed on for part of the attack, was most generous with its staff and time.

After two days of work the majestic walls of the Land Front, made of hard Bermuda limestone, are once again monumental features of Dockyard heritage. Along with the Casemate Barracks complex, these walls, three outworks, and the glacis were constructed from about 1820 to 1845. Unfortunately, the expansion of the Dockyard for the South Yard early in the 1900s called for the destruction of the Ravelin Tower, the Couvre Porte and part of the glacis. The hard rock below these redoubts was also quarried away, forming the great hole by the Shell fuel tanks. With the building of the Westgate Correctional Facility, the remainder of the glacis was removed, but the Right Advance, the outwork to the west, has survived.

astounding stonework of the Dockyard defences is unique in these islands. They are extraordinary monuments to all the Bermudians (slave and free), convicts from overseas, and the Royal Engineers, who laboured nigh on half a century in their construction. They have left a heritage site that has no parallel in the Americas. The eradication of invasive vegetation from these defence works must be completed, allowing all to stand proud once again.

To achieve that aim, a war footing must be maintained against these silent killers of heritage, these invaders and destroyers of Bermuda's natural and built legacies. It is time we woke up fully to this enemy within our midst.

From Abaco in the Bahamas comes a resonant, if plaintive, message:

133, Sandys MABX, or by telephone 734-1298.