The arrival of the nuclear submarine HMS Tireless at Portland this week has rekindled memories of the days when the island was a thriving naval base. Here, respected naval writer Roger Fry, from Upwey, writes about a major exercise that took place 50 years ago this week. The operation was notable for the arrival of the nuclear submarine USS Nautilus.

FIFTY years ago on September 30, the American destroyer depot ship USS Grand Canyon passed through the breakwater entrance into Portland harbour firing a 21-gun salute.

She was leading submarine tender USS Fulton, ammunition ship USS Shasta and a pair of Apache' Class ocean tugs Papago and Luisema, both modified for submarine rescue. This was an odd bunch, even for Portland!

The 10-day NATO exercise Strikeback had started on September 19, extending well into the North Atlantic from the Baltic, Channel and North Sea, which involved 75,000 fleet personnel, 200 warships and 650 aircraft simulating NATOs response to a mass breakout of Soviet submarines, aircraft and surface ships bent on attacking the West's trade routes - a typical Cold War' scenario.

The Blue Fleet included 300 merchant ships (including RMS Queen Elizabeth and SS Ile de France) on scheduled sailings, flying special flags to identify them as targets.

Most of the world's renowned warships participated, but none as famous as Portland's next arrival became. Such was the British Government's fear of the atom that permission had been refused for the world's first atomic' submarine to enter any British port within three miles of a large town and only then with a tug in permanent attendance. Forbidden to use Chatham, Devonport or Portsmouth naval bases, the Americans were nevertheless quite happy for USS Nautilus to lie quietly in the middle of Portland Harbour after her secret probing of the arctic ice in her attempt to reach the North Pole.

Under command of Commander WR Anderson USN, Nautilus had left the Electric Boat Company yard at Groton, Connecticut at 0800 on August 19 shrouded in secrecy. After clearing Block Island Sound, she dived deep on a high-speed northerly course which on the 30th found her off Jan Mayern Island, making contact with the diesel submarine USS Trigger by underwater telephone having covered 4.000 miles in II days.

Nautilus surfaced with Trigger and both continued to the ice edge. At 2000 hours on September 1, Nautilus made her first under-ice dive, descending several hundred feet as she travelled 150 miles due north. While attempting to surface through a polynia (hole in the ice), she damaged first No 2, then No I periscope. After returning to rendezvous with Trigger waiting at the ice edge, No 2 periscope was declared a write-off and so too was No I, but engineers set about straightening and rewelding its stainless steel barrel, taking more than 12 hours in a freezing 40-knot wind.

At 0800 on the 2nd, she again slipped under the ice to go 83 degrees - or further'. She in fact reached 87 degrees north, 180 miles from the Pole, before erratic gyro and other compasses forced her to turn back. By the time she reached Trigger she had covered 1,000 under-ice miles in 72 hours. Both boats then set course for Exercise Strikeback during which Nautilus sank' several capital ships, evading the anti-submarine forces to surface 40 miles east of Bishop Rock at midnight, September 30, having spent 14 days and four hours continuously submerged.

At 0830 October 1, IG57 USS Nautilus entered Portland Harbour to tie up alongside USS Fulton and throughout that day and the next, 21 US submarines rounded the Bill as Weymouth braced itself for thousands of dough-boys' on a week's R&R, social and sporting events organised by HMS Osprey and Adamant, the latter standing in for Portland's HMS Maidstone.

Early arrivals were USS Angler, Becuna, Jalloa, Sea Owl and Trumpetfish then Bergall, Chopper, Halfbeak, Sea Poacher and Trigger, with Darter on the 2nd. A second wave arrived a few days later - Barbero, Cavalla, Croaker, Grumper, Piper, Pompon, Ray, Redfin, Runner and Torsk. This was probably the largest fleet of US submarines seen in any spot outside the US and afforded a complete overview of submarine design from WW2 into the nuclear age. Under command of Comsubforlant' in his submarine flagship USS Piper, these, with others at Portsmouth, formed the basis of the Orange Fleet submarine threat.

Although Nautilus and others left early, Weymouth visitors took advantage of free weekend boat trips out to USS Fulton to see the remaining submarines at anchor, and some were fortunate aboard to look down on USS Barbero alongside the tender, missile hangar open, one Regulus missile within, the other undergoing maintenance on its launcher. Barbero had more than 1,000 successful launchings during her short career as a guided missile trials submarine and was the precursor of Polaris, Poseidon and now Trident ballistic missile submarines.

USS Nautilus returned to Portland the following year, to a razzamatazz welcome on the Coaling Pier having reached 90 North at 2315 Eastern Daylight Saving Time August 3, 1958 - but that's a story for 2008! Portland as a destination for nuclear submarines had begun.