The turmoil of 1968 helps Nixon win the presidency. Troop strength in Vietnam peaks and the draft accelerates. Karl Marlantes endures bitter jungle fighting on Hill 484, and draftee Arthur Wiknik gets a grim introduction to combat on 'Hamburger Hill'. But shortly after winning both hills, US troops abandon them.

The big blue is the world's greatest wilderness, far from shore and many kilometres deep. It's a vast marine desert where there is little to eat and nowhere to hide. Yet it's home to some of the biggest and most spectacular creatures on earth. This episode reveals what it takes to survive in this savage and forbidding world. We witness feats of incredible endurance, moments of high drama and extraordinary acts of heart-wrenching self-sacrifice. Every animal in the big blue must find their own unique way to survive. Sperm whales have the largest brains in the world. They live for 80 years, and we are only now beginning to learn the extraordinary complexity of their language of clicks - thought to coordinate the whole family in everything from childcare to hunting. With special pressure-proof cameras, we witness record-breaking feats of endurance as they hunt for squid a kilometre down into the abyss. Only recently have we begun to solve the mystery of where baby turtles disappear to in their early years. They leave the crowded waters of the coast and head to the open ocean, where they use floating debris like logs as life rafts. Here they remain until adulthood, adrift on the high seas in relative safety away from coastal predators. Over half of all animals in the open ocean drift in currents. Jellyfish cross entire oceans feeding on whatever happens to tangle with their tentacles. The jelly-like Portuguese man-of-war can harness sail power to fish with its deadly tentacles. Sometimes there is a brief explosion of food in this marine desert, but ocean hunters must be fast to make the best of this bonanza. We witness super pods of up to 5,000 spinner dolphins racing to herd vast shoals of lanternfish, briefly caught at the surface where it is thought they spawn. New aerial footage reveals, for the first time, the truth to a centuries-old sailors' legend of the 'boiling seas' - the spectacular feeding frenzy of 90kg tuna and dolphins smashing through the lantern fish shoals turning the sea white with foam.

The Earth was formed by a series of cosmic cataclysms including the most powerful blast in the Universe. Yet amid the turmoil our world was born. Could the same chain of events have created other earths elsewhere, inhabited by creatures like us?

This stylish mix of documentary and historical epic chronicles the reign of Commodus, the emperor whose rule marked the beginning of Rome's fall. In the first episode, the death of Marcus Aurelius brings a century of Roman triumphs and victories to an end, transferring power to his spoiled, unprepared son Commodus. When his father bequeaths him the world's mightiest empire, he is forced to spill the blood of both friends and enemies alike to keep his crown.

Journey through the long-vanished corners of prehistoric North America, beginning when man first entered the vast, unspoiled continent some 14,000 years ago, in this appealing BBC documentary. Witness ancient beasts, mammoths, mastodons, giant bears, and sabre-toothed cats, and see the legacies each has passed to their modern successors. Computer animation and digital effects bring to life mammoths, saber-toothed cats, giant ground sloths, short-faced bears, glyptodonts, and a plethora of smaller animals in a lush Ice Age mosaic.

What's your idea of the perfect birth? Do you want every medical intervention known to science or do you want to go it alone, without the help of a doctor or midwife? And what about after birth? Perhaps you'll hang on to your baby's placenta and carry it around with your newborn until it dries and drops off naturally? Or maybe you'll decide to eat it by whizzing it up into a smoothie? This film follows four pregnant women all making very different choices around their births, all determined to do it their way." 37-year-old Jo plans to deliver her baby completely alone on board her barge, without the assistance of any medical professional. By contrast, 34-year-old Anna is opting to sidestep the pains of labour and book in for a c-section at the Portland Hospital in London. Anna wants all the medication available and she doesn't want to feel a thing. There are plenty of unusual plans for after the birth too. In Devon, 33-year-old Lisa plans to lotus birth - she'll leave her baby's umbilical cord attached to its placenta and she'll keep it fresh by dusting it with salt, rose petals and lavender oil. 35-year-old Kati from Manchester is going to whizz her afterbirth into a smoothie and consume it over a number of days. She hopes it will help her stave off post-natal baby blues and bounce back as quickly as possible. Fending off bewildered looks and concerns from friends, family and medical professionals, each woman is going against convention to have the birth she wants. There are free and frank discussions between mums and daughters and decisions to go against medical advice. So does breaking with the norm and sticking to your guns pay off? And what really is the perfect birth?